diff --git a/_docs/credits.html b/_docs/credits.html
index 261f47924b65b05dfdb14634efc29a8892797584..09c6526c6e401892f7fd4f8d5f7e7f0a143e83a8 100644
--- a/_docs/credits.html
+++ b/_docs/credits.html
@@ -87,7 +87,7 @@
 <hr>
 <p><a href="privacy_oc.html">Open Camera Privacy Policy.</a></p>
 <p>This website uses icons from third party sources, see <a href="index.html#licence">licences.</a></p>
-<p><a href="http://sourceforge.net/p/opencamera/">Open Camera on Sourceforge.</a></p>
+<p><a href="https://sourceforge.net/projects/opencamera/">Open Camera on Sourceforge.</a></p>
 <hr>
 
 </body>
diff --git a/_docs/devices.html b/_docs/devices.html
index bc99d5cfd737471b0843c0f06b776ce74db924a7..73f7d679e711bf0f2fe051647f6ff5501c38bc5e 100644
--- a/_docs/devices.html
+++ b/_docs/devices.html
@@ -109,14 +109,6 @@
 <p>I've also had reports of RAW/DNG images being saved with red/blue swapped. See
 <a href="https://sourceforge.net/p/opencamera/tickets/422/">here</a> for details.</p>
 
-<h3>Lenovo Vibe S1</h3>
-
-<p>A special prize goes to this device - several people have told me they can't even install Open Camera (Google Play
-        gives error 504) on at least some versions of this device. This appears to be due to a pre-installed app "Stereo Verify"
-        that clashes with Open Camera's package name (net.sourceforge.opencamera), which prevents installation of Open Camera.
-        Also see
-        <a href="http://forum.xda-developers.com/vibe-p1/help/stereo-verify-t3454811">here</a> for further discussion.</p>
-
 <h3>Nokia</h3>
 
 <p>I've tested Open Camera with the Nokia 8. Everything seems to work as far as I can tell, including Camera2 API with full
@@ -229,7 +221,7 @@ in general this is likely available for the flagship S devices running Android 1
 <hr>
 <p><a href="privacy_oc.html">Open Camera Privacy Policy.</a></p>
 <p>This website uses icons from third party sources, see <a href="index.html#licence">licences.</a></p>
-<p><a href="http://sourceforge.net/p/opencamera/">Open Camera on Sourceforge.</a></p>
+<p><a href="https://sourceforge.net/projects/opencamera/">Open Camera on Sourceforge.</a></p>
 <hr>
 
 </body>
diff --git a/_docs/help.html b/_docs/help.html
index 6677eb0dfe9e163f3fe38c1bc2be633c8506a37f..e52cd707963cb618e42ddfc94824a46c584f19c3 100644
--- a/_docs/help.html
+++ b/_docs/help.html
@@ -150,8 +150,7 @@ a panel with various controls:</p><ul>
     <li>
         <b>ISO (top row)</b> - (Not supported on all devices.) A higher ISO setting means the camera is more sensitive to light, though may
         also result in more noise. This mimics the film speed on traditional film cameras. Select "AUTO" to switch back to
-        automatic ISO mode. See
-        <a href="http://digital-photography-school.com/iso-settings">here</a> for more details on ISO.
+        automatic ISO mode.
         If Camera2 API is used, then selecting a non-auto ISO will bring up sliders allowing direct control over the ISO and exposure
         time (in place of the exposure compensation slider). You can also select "M" to switch straight to manual mode, keeping to the
         current ISO value.
@@ -160,7 +159,7 @@ a panel with various controls:</p><ul>
         <b>Exposure compensation (slider)</b> - A higher value increases the exposure, so that pictures come out brighter in low light; a
         lower value makes pictures darker. One unit of EV changes the brightness of the captured image by a factor of two. +1 EV
         doubles the image brightness, while -1 EV halves the image brightness. Set to 0 for the default exposure.
-        See <a href="http://en.wikipedia.org/wiki/Exposure_compensation">Exposure compensation</a>.
+        See <a href="https://en.wikipedia.org/wiki/Exposure_compensation">Exposure compensation</a>.
         (Only available if the camera supports control of the exposure.)
     </li>
     <li>
@@ -242,7 +241,7 @@ will be available which instead work by making the screen light up (note, front
             <li><b>X-Bokeh:</b> Blurs the background of photos. This is typically intended when taking portraits of people.</li>
             <li><b>X-Bty:</b> Face retouch or "beauty", applies cosmetic effects to people's faces.</li>
         </ul>
-        Note many features are unavailable when using an extension mode, including flash, zoom and manual controls.
+        Note many features may be unavailable when using an extension mode, including flash, zoom and manual controls.
     </li>
 </ul></li>
 <li><b>Auto-level</b> - Enable the auto-level feature for photos (see
@@ -263,9 +262,8 @@ Settings/Timer.</li>
 interval between each repeated photo can be set under Settings/"Repeat mode interval".</li>
 <li><b>Grid</b> - Whether to display one of a choice of grids on the camera preview. Also available
 under Settings/Camera preview/"Show a grid".</li>
-<li><b>White balance</b> - Choose a method to control how the white balance is set. See
-<a href="http://digital-photography-school.com/introduction-to-white-balance">here</a> for an
-explanation of white balance. (Only available if the camera supports different white balance
+<li><b>White balance</b> - Choose a method to control how the white balance is set.
+(Only available if the camera supports different white balance
 settings.) If Camera2 API is enabled, then you can also set "manual". In this mode, manual
 control over the white balance temperature is available from the exposure compensation icon
 <img src="ic_exposure_white_48dp.png" alt="Exposure Compensation icon" width="32" height="32">.</li>
@@ -451,8 +449,7 @@ captured.</p>
 
 <p><b>Apply a scene mode</b> - Choose a scene mode to apply. (Only available if the camera supports scene modes.)</p>
 
-<p><b>Set the white balance</b> - Choose a method to control how the white balance is set. See
-<a href="http://digital-photography-school.com/introduction-to-white-balance">here</a> for an explanation of white balance. (Only
+<p><b>Set the white balance</b> - Choose a method to control how the white balance is set. (Only
 available if the camera supports different white balance settings.)</p>-->
 
 <!--<p><b>Set the exposure compensation</b> - A higher value increases the exposure,
@@ -462,8 +459,7 @@ darker. Set to 0 for the default exposure. See
 (Only available if the camera supports control of the exposure.)</p>-->
 
 <!--<p><b>Set the ISO</b> - A higher ISO setting means the camera is more sensitive to light, though may also result in more
-noise. This mimics the film speed on traditional film cameras. Note that this setting may not be supported on all cameras.
-See <a href="http://digital-photography-school.com/iso-settings">here</a> for more details on ISO.</p>
+noise. This mimics the film speed on traditional film cameras. Note that this setting may not be supported on all cameras.</p>
 
 <p><b>Auto-level</b> - Enable the auto-level features for photos (see <a href="#auto_stabilise">above</a>). (Only available
 if the device has enough memory.)</p>-->
@@ -495,9 +491,8 @@ Fast Burst photo mode, or long press the "take photo" button in Standard or Fast
 
 <p><b>More camera controls...</b> - Select to access the following controls:</p>
 
-<p><b>Touch to capture</b> - This option allows you to take a photo either just by touching or double-tapping on the
-preview screen. Note that starting/stopping video recording is still performed in the normal way; this option only
-affects taking photos.</p>
+<p><b>Touch to capture</b> - This option allows you to take a photo, or start and stop video recording,
+    just by either touching or double-tapping on the preview screen.</p>
 
 <p><b>Pause after taking photo</b> - If ticked, after taking a photo the display will pause, with options to share
 <img src="share.png" alt="Share icon" width="32" height="32"> or delete
@@ -704,11 +699,11 @@ choose the colours of the stripes.</p>
 <p><b>Show a grid</b> - Whether to display one of a choice of grids on the camera preview. Grids are useful in photography to help
     compose your image. Options are:</p>
 <ul>
-    <li>3x3 - helps with applying the <a href="http://en.wikipedia.org/wiki/Rule_of_thirds">rule of thirds</a>.</li>
+    <li>3x3 - helps with applying the <a href="https://en.wikipedia.org/wiki/Rule_of_thirds">rule of thirds</a>.</li>
     <li>Phi 3x3 - 3x3 grid with ratios 1:0.618:1.</li>
     <li>4x2</li>
     <li>Crosshair</li>
-    <li>Golden - displays a <a href="http://en.wikipedia.org/wiki/Golden_spiral">Golden spiral</a> (or technically,
+    <li>Golden - displays a <a href="https://en.wikipedia.org/wiki/Golden_spiral">Golden spiral</a> (or technically,
         a Fibonacci spiral). You can use this to improve your photography.</li>
     <li>Golden Triangles</li>
     <li>Diagonals</li>
@@ -1250,9 +1245,8 @@ inside /storage/ (press "Parent Folder" until you're in "/storage/") or
 of the folders in there - note that confusingly it won't be "sdcard", but will be named something else,
 e.g., "extSdCard".</li>
 <li><b>Android 4.4</b> - Unfortunately it is not possible for 3rd party apps to write to external SD cards.
-<b>This is not a bug or missing feature in Open Camera</b>, rather that
-<a href="http://www.androidpolice.com/2014/02/17/external-blues-google-has-brought-big-changes-to-sd-cards-in-kitkat-and-even-samsung-may-be-implementing-them/">Google
-have blocked write access to external SD cards in Android 4.4</a>.</li>
+<b>This is not a bug or missing feature in Open Camera</b>, rather that access to external SD cards was
+blocked in Android 4.4, and new methods to access them did not appear until Android 5.</li>
 <li><b>Android 5.0 onwards</b> - The restrictions on SD cards introduced in Android 4.4 still apply, however
 instead you can enable Settings/More camera controls/"Storage Access Framework", and this should allow you
 to save to external SD cards. If when choosing a folder, you only see "Recent", you may need to click on the
@@ -1303,13 +1297,25 @@ option is on. (If they're being rotated even when the phone is held level, it ma
 device isn't calibrated.) It's off by default, but you may have accidentally switched it on. To turn off, go to the "popup" menu
 and untick Auto-level.</p>
 
-<p><b>Why doesn't Open Camera support dual / multiple cameras?</b> - Open Camera supports switching between all cameras
-that are made available to third party applications. Usually this means front and back cameras, but some devices have
-multiple front and/or back-facing cameras. Use the
-<img src="baseline_add_a_photo_white_48.png" alt="Switch multi-camera icon" width="16" height="16">switch multi-camera icon
-to switch between multiple front or back cameras. Note that some devices do not expose the multiple cameras explicitly,
-but instead will automatically switch cameras as required when zooming in or out. In some cases the extra cameras aren't
-made available to third party applications, so it isn't possible for Open Camera to support them.</p>
+<p><b>Why doesn't Open Camera support dual / multiple cameras?</b> - Open Camera supports cameras
+    that are made available to third party applications, although you may need to set Settings/"Camera API"
+    to "Camera2 API". When using Camera2 API. many devices expose multiple cameras via the zoom - zooming out to less
+    than 1x switches to the ultra-wide camera, zooming in automatically switches to the telephoto when
+    required. On other devices, the cameras can be manually switched by using the
+    <img src="baseline_add_a_photo_white_48.png" alt="Switch multi-camera icon" width="16" height="16">switch multi-camera icon.
+    Note that some devices don't allow third party applications to use their extra cameras, either
+    via zoom or by explicitly switching to the camera. In such cases Open Camera cannot access them.</p>
+
+<p><b>But another third party camera app can access the extra cameras on my device, why can't Open Camera?</b> -
+    On some devices, it may be possible to access the camera by ignoring what the device claims, and trying to
+    access the camera IDs anyway. This is a hack - on other devices, this will lead to buggy behaviour where
+    cameras are exposed that hang or otherwise don't work. The problem here is that the device does not
+    support exposing the cameras to third party camera applications via the Android camera API.</p>
+
+<p><b>But can't you use the hacky method to access the extra cameras anyway?</b> - Put it this way:
+    you paid hundreds of pounds for a device from a large company with lots of resources, but you
+    want the free application to do the extra work to workaround the device's limitation, even when it's a hacky
+    method? Sometimes I do implement workarounds for device limitations - but it is risky to do so here.</p>
 
 <p><b>Why doesn't Open Camera support the maximum video resolution on my device?</b> - If you
 are using Camera2 API, make sure that you're not in slow motion mode (see "Speed" under
@@ -1500,7 +1506,7 @@ It is helpful to supply the "About" information - please go to Settings/About, t
 can paste the information into your web browser, email or whatever.</p>
 
 <p>For more general questions or things like feature suggestions, please use the
-<a href="http://sourceforge.net/p/opencamera/discussion/">forums</a>.
+<a href="https://sourceforge.net/p/opencamera/discussion/">forums</a>.
 For some enquiries you may prefer to use email.
 Please contact me at <a href="mailto:mark.harman.apps@gmail.com?subject=Open%20Camera">mark.harman.apps@gmail.com</a>.
     <!-- if I change my email, remember also to update the contact for privacy policy
@@ -1515,7 +1521,7 @@ miss it, there's only limited number of characters for me to reply).</p>
 <hr>
 <p><a href="privacy_oc.html">Open Camera Privacy Policy.</a></p>
 <p>This website uses icons from third party sources, see <a href="index.html#licence">licences.</a></p>
-<p><a href="http://sourceforge.net/p/opencamera/">Open Camera on Sourceforge.</a></p>
+<p><a href="https://sourceforge.net/projects/opencamera/">Open Camera on Sourceforge.</a></p>
 <hr>
 
 </body>
diff --git a/_docs/history.html b/_docs/history.html
index 0a9bde2b3cee5a1d42fe905c2aee91a238599e8e..c34d512ea3b3ff48c0e78b5283f50e318fdaf63c 100644
--- a/_docs/history.html
+++ b/_docs/history.html
@@ -47,6 +47,39 @@
 <p>&lt; <small><a href="index.html">Main Page.</a></small></p>
 
 <pre>
+Version 1.52 (2023/08/13)
+
+FIXED   Crash related to multi-camera devices.
+FIXED   Possible crash when failing to save with Storage Access Framework.
+FIXED   Jittery zoom when using multitouch pinch but pinching slowly.
+FIXED   Don't show zebra stripes, focus peaking or histogram, when displaying resultant photo for
+        "Pause after taking photo" option.
+FIXED   Problem where clicking on gallery icon would sometimes go to a "base" image instead of HDR
+        image, when saving HDR photos with base images (for Android 10+).
+FIXED   Collapse notification panel when launching from a quick settings tile.
+FIXED   Some info toasts weren't showing (e.g., when cancelling SAF dialog, or denying location
+        permission).
+FIXED   Problem where if setting Video Picture Profiles to non-default value caused camera to fail
+        to open, the Video Picture Profiles setting would no longer show to be able to set back to
+        default.
+FIXED   Allow trying to switch between photo and video mode if camera fails to open (in some case
+        the failure may be specific to the mode).
+FIXED   Aspect ratio and other fixes in split-screen and multi-window modes.
+FIXED   Problem on some tablets where zoom seekbar showed under navigation bar in landscape
+        orientation in some circumstances.
+ADDED   Support for zoom with camera vendor extensions (for supported Android 13+ devices).
+ADDED   Support for displaying on-screen ISO and exposure time with camera vendor extensions (for
+        supported Android 13+ devices).
+UPDATED Made pinch zoom more sensitive (better support for modern devices with higher zoom levels).
+UPDATED "Touch to capture" option now supports starting and stopping video.
+UPDATED Applied a timeout of 2 second for focusing with original camera API.
+UPDATED Improved performance for NR photo mode.
+UPDATED Drop support for notifications for background saving, due to Android 13 permissions faff.
+UPDATED No longer allow a screenshot of the camera preview to show in "recent apps" view (for
+        Android 13+).
+UPDATED No longer cancel panorama when moving device orientation too far in wrong direction.
+UPDATED Made more text scale according to user's font size preference.
+
 Version 1.51.1 (2023/01/02)
 
 FIXED   Fix crashes for Camera2 API.
@@ -1780,7 +1813,7 @@ First release.
 <hr>
 <p><a href="privacy_oc.html">Open Camera Privacy Policy.</a></p>
 <p>This website uses icons from third party sources, see <a href="index.html#licence">licences.</a></p>
-<p><a href="http://sourceforge.net/p/opencamera/">Open Camera on Sourceforge.</a></p>
+<p><a href="https://sourceforge.net/projects/opencamera/">Open Camera on Sourceforge.</a></p>
 <hr>
 
 </body>
diff --git a/_docs/index.html b/_docs/index.html
index 4eadf078568901d575ad92fac201417e130574f5..c439797d71917e33a74e4415c3b0e25f4bc63a51 100644
--- a/_docs/index.html
+++ b/_docs/index.html
@@ -137,8 +137,8 @@ browsers -->
 
 <hr>
 <p>
-<a href="http://sourceforge.net/p/opencamera/blog/">Open Camera Blog</a> ~
-<a href="http://sourceforge.net/p/opencamera/discussion/">Discussion Forums</a> ~
+<a href="https://sourceforge.net/p/opencamera/blog/">Open Camera Blog</a> ~
+<a href="https://sourceforge.net/p/opencamera/discussion/">Discussion Forums</a> ~
 <a href="https://sourceforge.net/p/opencamera/code/">Code Repository (Git)</a>
 </p>
 
@@ -198,7 +198,7 @@ your wedding etc :)</p>
 <!-- also linked from other pages on this site, and Google Play store listing -->
 <!-- we also say Terms of Service due to the Google unwanted software policy -->
 
-<p>Open Camera is released under the <a href="http://www.gnu.org/copyleft/gpl.html">GPL v3 or later</a>. The source code is
+<p>Open Camera is released under the <a href="https://www.gnu.org/licenses/gpl-3.0.html">GPL v3 or later</a>. The source code is
 available from
 <!-- use &#8203; to limit widths on continuous text to 30 characters, to avoid messing up view on mobile devices -->
 <a href="https://sourceforge.net/projects/opencamera/files/">https://sourceforge.net/&#8203;projects/opencamera/files/</a> .
@@ -307,7 +307,7 @@ of old versions; but no need to mention CC0 media which doesn't require attribut
 <hr>
 <p><a href="privacy_oc.html">Open Camera Privacy Policy.</a></p>
 <p>This website uses icons from third party sources, see <a href="index.html#licence">licences.</a></p>
-<p><a href="http://sourceforge.net/p/opencamera/">Open Camera on Sourceforge.</a></p>
+<p><a href="https://sourceforge.net/projects/opencamera/">Open Camera on Sourceforge.</a></p>
 <hr>
 
 </body>
diff --git a/_docs/info.html b/_docs/info.html
index 91c2124f99d4e4ab60c7d8a3bb5202cbda9dbb39..64fd5214b553da25ecf373e2c0a81c3e19177776 100644
--- a/_docs/info.html
+++ b/_docs/info.html
@@ -76,7 +76,7 @@
 <hr>
 <p><a href="privacy_oc.html">Open Camera Privacy Policy.</a></p>
 <p>This website uses icons from third party sources, see <a href="index.html#licence">licences.</a></p>
-<p><a href="http://sourceforge.net/p/opencamera/">Open Camera on Sourceforge.</a></p>
+<p><a href="https://sourceforge.net/projects/opencamera/">Open Camera on Sourceforge.</a></p>
 <hr>
 
 </body>
diff --git a/_docs/privacy_oc.html b/_docs/privacy_oc.html
index 48728d312ceeef5ab4edf66267619d0ebd875a1c..14c3082b3886a85ddfa4cbc0decf9b1fe858c70b 100644
--- a/_docs/privacy_oc.html
+++ b/_docs/privacy_oc.html
@@ -81,7 +81,7 @@ of taking photos and recording videos, to fulfil its purpose as a camera. Microp
         When enabled, audio data is likely to be sent to remote servers by Android to perform speech recognition.
         This is subject to the Data Processing Addendum for Products where Google is a Data Processor,
         located at
-        <a href="https://privacy.google.com/businesses/gdprprocessorterms/">https://privacy.google.com/businesses/gdprprocessorterms/</a> , as updated from time to time.
+        <small><a href="https://privacy.google.com/businesses/gdprprocessorterms/">https://privacy.google.com/businesses/gdprprocessorterms/</a></small> , as updated from time to time.
         This option is no longer available in version 1.50 onwards.
     </li>
     <li>For versions 1.49.2 or earlier: The "addresses" option for photo stamp or video subtitles used the Android
@@ -120,7 +120,7 @@ that use our services"</a>.</p>
 <hr>
 <p><a href="privacy_oc.html">Open Camera Privacy Policy.</a></p>
 <p>This website uses icons from third party sources, see <a href="index.html#licence">licences.</a></p>
-<p><a href="http://sourceforge.net/p/opencamera/">Open Camera on Sourceforge.</a></p>
+<p><a href="https://sourceforge.net/projects/opencamera/">Open Camera on Sourceforge.</a></p>
 <hr>
 
 </body>
diff --git a/app/build.gradle b/app/build.gradle
index 4814d5afa11bb7409e12236983123cab2144a74a..3900d36317a0b1199a4374fce581f6599f4668bf 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -77,6 +77,8 @@ dependencies {
     implementation 'androidx.exifinterface:exifinterface:1.3.7'
     implementation 'foundation.e:elib:0.0.1-alpha11'
 
+    implementation 'androidx.exifinterface:exifinterface:1.3.6'
+
     testImplementation 'junit:junit:4.13.2'
 
     // newer AndroidJUnit4 InstrumentedTest
diff --git a/app/src/androidTest/java/net/sourceforge/opencamera/InstrumentedTest.java b/app/src/androidTest/java/net/sourceforge/opencamera/InstrumentedTest.java
index cc26f5496256554b6359c0090920b4dc914cfbe4..cbb9834346b3a69afdb1dfab1160ee5d51287336 100644
--- a/app/src/androidTest/java/net/sourceforge/opencamera/InstrumentedTest.java
+++ b/app/src/androidTest/java/net/sourceforge/opencamera/InstrumentedTest.java
@@ -59,8 +59,6 @@ interface PanoramaTests {}
 public class InstrumentedTest {
 
     private static final String TAG = "InstrumentedTest";
-    public static final boolean test_camera2 = false;
-    //public static final boolean test_camera2 = true;
 
     static final Intent intent;
     static {
@@ -70,7 +68,7 @@ public class InstrumentedTest {
         intent.putExtra("test_project_junit4", true);
 
         // need to run this here, not in before(), so it's run before activity is created (otherwise Camera2 won't be enabled)
-        TestUtils.initTest(ApplicationProvider.getApplicationContext(), test_camera2);
+        TestUtils.initTest(ApplicationProvider.getApplicationContext());
     }
 
     @Rule
@@ -106,7 +104,7 @@ public class InstrumentedTest {
         // state after running tests.
         mActivityRule.getScenario().onActivity(activity -> {
             Log.d(TAG, "after: init");
-            TestUtils.initTest(activity, test_camera2);
+            TestUtils.initTest(activity);
         });
 
         Log.d(TAG, "after done");
@@ -456,7 +454,8 @@ public class InstrumentedTest {
             TestUtils.checkHDROffsets(activity, exp_offsets_x, exp_offsets_y);
 
             //checkHistogramDetails(hdrHistogramDetails, 3, 43, 251);
-            checkHistogramDetails(hdrHistogramDetails, 6, 42, 251);
+            //checkHistogramDetails(hdrHistogramDetails, 6, 42, 251);
+            checkHistogramDetails(hdrHistogramDetails, 6, 49, 252);
         });
     }
 
@@ -709,7 +708,7 @@ public class InstrumentedTest {
 
             //checkHistogramDetails(hdrHistogramDetails, 0, 48, 255);
             //checkHistogramDetails(hdrHistogramDetails, 0, 65, 255);
-            checkHistogramDetails(hdrHistogramDetails, 0, 62, 254);
+            checkHistogramDetails(hdrHistogramDetails, 0, 72, 255);
         });
     }
 
@@ -1012,8 +1011,8 @@ public class InstrumentedTest {
             int [] exp_offsets_y = {0, 0};
             TestUtils.checkHDROffsets(activity, exp_offsets_x, exp_offsets_y);
 
-            //checkHistogramDetails(hdrHistogramDetails, 13, 72, 250);
-            checkHistogramDetails(hdrHistogramDetails, 24, 72, 250);
+            //checkHistogramDetails(hdrHistogramDetails, 33, 78, 250);
+            checkHistogramDetails(hdrHistogramDetails, 17, 75, 250);
         });
     }
 
@@ -1065,7 +1064,7 @@ public class InstrumentedTest {
 
             //checkHistogramDetails(hdrHistogramDetails, 17, 81, 255);
             //checkHistogramDetails(hdrHistogramDetails, 32, 74, 255);
-            checkHistogramDetails(hdrHistogramDetails, 29, 68, 255);
+            checkHistogramDetails(hdrHistogramDetails, 23, 71, 255);
         });
     }
 
@@ -1092,8 +1091,8 @@ public class InstrumentedTest {
             int [] exp_offsets_y = {0, 0, 0, 0};
             TestUtils.checkHDROffsets(activity, exp_offsets_x, exp_offsets_y);
 
-            //checkHistogramDetails(hdrHistogramDetails, 15, 69, 254);
-            checkHistogramDetails(hdrHistogramDetails, 24, 70, 254);
+            //checkHistogramDetails(hdrHistogramDetails, 31, 75, 254);
+            checkHistogramDetails(hdrHistogramDetails, 23, 74, 254);
         });
     }
 
@@ -1123,7 +1122,8 @@ public class InstrumentedTest {
 
             //checkHistogramDetails(hdrHistogramDetails, 17, 81, 255);
             //checkHistogramDetails(hdrHistogramDetails, 28, 82, 255);
-            checkHistogramDetails(hdrHistogramDetails, 21, 74, 255);
+            //checkHistogramDetails(hdrHistogramDetails, 21, 74, 255);
+            checkHistogramDetails(hdrHistogramDetails, 17, 74, 255);
         });
     }
 
@@ -1152,8 +1152,8 @@ public class InstrumentedTest {
             int [] exp_offsets_y = {0, 0, 0, 0, 0, 0};
             TestUtils.checkHDROffsets(activity, exp_offsets_x, exp_offsets_y);
 
-            //checkHistogramDetails(hdrHistogramDetails, 15, 70, 254);
-            checkHistogramDetails(hdrHistogramDetails, 25, 71, 254);
+            //checkHistogramDetails(hdrHistogramDetails, 32, 76, 254);
+            checkHistogramDetails(hdrHistogramDetails, 25, 75, 254);
         });
     }
 
@@ -1943,7 +1943,8 @@ public class InstrumentedTest {
 
             TestUtils.HistogramDetails hdrHistogramDetails = TestUtils.subTestHDR(activity, inputs, "testHDR47_exp5_output.jpg", false, -1, -1);
 
-            checkHistogramDetails(hdrHistogramDetails, 1, 73, 255);
+            //checkHistogramDetails(hdrHistogramDetails, 1, 73, 255);
+            checkHistogramDetails(hdrHistogramDetails, 1, 80, 255);
         });
     }
 
@@ -1970,7 +1971,8 @@ public class InstrumentedTest {
 
             TestUtils.HistogramDetails hdrHistogramDetails = TestUtils.subTestHDR(activity, inputs, "testHDR47_exp7_output.jpg", false, -1, -1);
 
-            checkHistogramDetails(hdrHistogramDetails, 1, 73, 255);
+            //checkHistogramDetails(hdrHistogramDetails, 1, 73, 255);
+            checkHistogramDetails(hdrHistogramDetails, 1, 80, 255);
         });
     }
 
@@ -2019,7 +2021,8 @@ public class InstrumentedTest {
 
             TestUtils.HistogramDetails hdrHistogramDetails = TestUtils.subTestHDR(activity, inputs, "testHDR48_exp5_output.jpg", false, -1, -1);
 
-            checkHistogramDetails(hdrHistogramDetails, 0, 59, 241);
+            //checkHistogramDetails(hdrHistogramDetails, 0, 59, 241);
+            checkHistogramDetails(hdrHistogramDetails, 0, 67, 241);
         });
     }
 
@@ -2040,7 +2043,8 @@ public class InstrumentedTest {
 
             TestUtils.HistogramDetails hdrHistogramDetails = TestUtils.subTestHDR(activity, inputs, "testHDR49_exp2_output.jpg", false, -1, -1);
 
-            checkHistogramDetails(hdrHistogramDetails, 0, 92, 250);
+            //checkHistogramDetails(hdrHistogramDetails, 12, 120, 251);
+            checkHistogramDetails(hdrHistogramDetails, 0, 122, 251);
         });
     }
 
@@ -2064,7 +2068,7 @@ public class InstrumentedTest {
             TestUtils.HistogramDetails hdrHistogramDetails = TestUtils.subTestHDR(activity, inputs, "testHDR49_output.jpg", false, -1, -1);
 
             //checkHistogramDetails(hdrHistogramDetails, 0, 75, 255);
-            checkHistogramDetails(hdrHistogramDetails, 0, 81, 254);
+            checkHistogramDetails(hdrHistogramDetails, 0, 89, 254);
         });
     }
 
@@ -2087,8 +2091,7 @@ public class InstrumentedTest {
 
             TestUtils.HistogramDetails hdrHistogramDetails = TestUtils.subTestHDR(activity, inputs, "testHDR49_exp4_output.jpg", false, -1, -1);
 
-            //checkHistogramDetails(hdrHistogramDetails, 0, 100, 245);
-            checkHistogramDetails(hdrHistogramDetails, 0, 94, 244);
+            checkHistogramDetails(hdrHistogramDetails, 19, 109, 244);
         });
     }
 
@@ -2113,7 +2116,8 @@ public class InstrumentedTest {
             TestUtils.HistogramDetails hdrHistogramDetails = TestUtils.subTestHDR(activity, inputs, "testHDR49_exp5_output.jpg", false, -1, -1);
 
             //checkHistogramDetails(hdrHistogramDetails, 0, 72, 244);
-            checkHistogramDetails(hdrHistogramDetails, 0, 78, 243);
+            //checkHistogramDetails(hdrHistogramDetails, 0, 78, 243);
+            checkHistogramDetails(hdrHistogramDetails, 0, 87, 243);
         });
     }
 
@@ -2202,7 +2206,7 @@ public class InstrumentedTest {
             TestUtils.HistogramDetails hdrHistogramDetails = TestUtils.subTestHDR(activity, inputs, "testHDR53_output.jpg", false, 103, 1000000000L/5381);
 
             //checkHistogramDetails(hdrHistogramDetails, 0, 55, 254);
-            checkHistogramDetails(hdrHistogramDetails, 0, 64, 255);
+            checkHistogramDetails(hdrHistogramDetails, 0, 72, 255);
         });
     }
 
@@ -2381,7 +2385,7 @@ public class InstrumentedTest {
 
             TestUtils.HistogramDetails hdrHistogramDetails = TestUtils.subTestHDR(activity, inputs, "testHDR61_output.jpg", false, 50, 1000000000L/5025);
 
-            checkHistogramDetails(hdrHistogramDetails, 0, 86, 254);
+            checkHistogramDetails(hdrHistogramDetails, 0, 93, 255);
 
             int [] exp_offsets_x = {0, 0, 1};
             int [] exp_offsets_y = {0, 0, -2};
@@ -6308,6 +6312,7 @@ public class InstrumentedTest {
             }
         });
     }
+
     /** Tests option to remove device exif info, but keeping datetime tags.
      */
     @Category(PhotoTests.class)
diff --git a/app/src/androidTest/java/net/sourceforge/opencamera/TestUtils.java b/app/src/androidTest/java/net/sourceforge/opencamera/TestUtils.java
index 0e5182e8ecd3011463238a9534f0b58a87839219..430c616293abe6b058d4f8acf205c73d9738cd7b 100644
--- a/app/src/androidTest/java/net/sourceforge/opencamera/TestUtils.java
+++ b/app/src/androidTest/java/net/sourceforge/opencamera/TestUtils.java
@@ -54,6 +54,9 @@ import foundation.e.camera.R;
 public class TestUtils {
     private static final String TAG = "TestUtils";
 
+    public static final boolean test_camera2 = false;
+    //public static final boolean test_camera2 = true;
+
     final private static String images_base_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM).getAbsolutePath();
     final public static String hdr_images_path = images_base_path + "/testOpenCamera/testdata/hdrsamples/";
     final public static String avg_images_path = images_base_path + "/testOpenCamera/testdata/avgsamples/";
@@ -66,7 +69,7 @@ public class TestUtils {
 
     /** Code to call before running each test.
      */
-    public static void initTest(Context context, boolean test_camera2) {
+    public static void initTest(Context context) {
         Log.d(TAG, "initTest: " + test_camera2);
         // initialise test statics (to avoid the persisting between tests in a test suite run!)
         MainActivity.test_preview_want_no_limits = false;
@@ -566,9 +569,10 @@ public class TestUtils {
 
         Bitmap nr_bitmap;
         try {
+            HDRProcessor hdrProcessor = activity.getApplicationInterface().getHDRProcessor();
             // initialise allocation from first two bitmaps
-            //int inSampleSize = activity.getApplicationInterface().getHDRProcessor().getAvgSampleSize(inputs.size());
-            int inSampleSize = activity.getApplicationInterface().getHDRProcessor().getAvgSampleSize(iso, exposure_time);
+            //int inSampleSize = hdrProcessor.getAvgSampleSize(inputs.size());
+            int inSampleSize = hdrProcessor.getAvgSampleSize(iso, exposure_time);
             Bitmap bitmap0 = getBitmapFromFile(activity, inputs.get(0), inSampleSize);
             Bitmap bitmap1 = getBitmapFromFile(activity, inputs.get(1), inSampleSize);
             int width = bitmap0.getWidth();
@@ -577,8 +581,7 @@ public class TestUtils {
             float avg_factor = 1.0f;
             List<Long> times = new ArrayList<>();
             long time_s = System.currentTimeMillis();
-            HDRProcessor.AvgData avg_data = activity.getApplicationInterface().getHDRProcessor().processAvg(bitmap0, bitmap1, avg_factor, iso, exposure_time, zoom_factor);
-            Allocation allocation = avg_data.allocation_out;
+            HDRProcessor.AvgData avg_data = hdrProcessor.processAvg(bitmap0, bitmap1, avg_factor, iso, exposure_time, zoom_factor);
             times.add(System.currentTimeMillis() - time_s);
             // processAvg recycles both bitmaps
             if( cb != null ) {
@@ -591,7 +594,7 @@ public class TestUtils {
                 Bitmap new_bitmap = getBitmapFromFile(activity, inputs.get(i), inSampleSize);
                 avg_factor = (float)i;
                 time_s = System.currentTimeMillis();
-                activity.getApplicationInterface().getHDRProcessor().updateAvg(avg_data, width, height, new_bitmap, avg_factor, iso, exposure_time, zoom_factor);
+                hdrProcessor.updateAvg(avg_data, width, height, new_bitmap, avg_factor, iso, exposure_time, zoom_factor);
                 times.add(System.currentTimeMillis() - time_s);
                 // updateAvg recycles new_bitmap
                 if( cb != null ) {
@@ -600,7 +603,7 @@ public class TestUtils {
             }
 
             time_s = System.currentTimeMillis();
-            nr_bitmap = activity.getApplicationInterface().getHDRProcessor().avgBrighten(allocation, width, height, iso, exposure_time);
+            nr_bitmap = hdrProcessor.avgBrighten(avg_data, width, height, iso, exposure_time);
             avg_data.destroy();
             //noinspection UnusedAssignment
             avg_data = null;
@@ -1155,9 +1158,9 @@ public class TestUtils {
         else if( is_nr ) {
             suffix = "_NR";
             if( activity.getApplicationInterface().getNRModePref() == MyApplicationInterface.NRModePref.NRMODE_LOW_LIGHT )
-                max_time_s += 6; // takes longer to save low light photo
+                max_time_s += 11; // takes longer to save low light photo
             else
-                max_time_s += 5;
+                max_time_s += 10;
         }
         else if( is_expo ) {
             suffix = "_" + (n_expo_images-1);
@@ -1216,8 +1219,9 @@ public class TestUtils {
             Log.d(TAG, "expected name1: " + expected_filename1);
             assertTrue(expected_filename.equals(saved_image_file.getName()) || expected_filename1.equals(saved_image_file.getName()));*/
             // allow for possibility that the time has passed since taking the photo
+            // but start from -1, as time may have passed in the Test code since saving the file
             boolean matched = false;
-            for(int i=0;i<=max_time_s && !matched;i++) {
+            for(int i=-1;i<=max_time_s && !matched;i++) {
                 Date test_date = new Date(date.getTime() - 1000L *i);
                 String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss", Locale.US).format(test_date);
                 String expected_filename = "IMG_" + timeStamp + suffix + ".jpg";
diff --git a/app/src/androidTest/java/net/sourceforge/opencamera/test/MainActivityTest.java b/app/src/androidTest/java/net/sourceforge/opencamera/test/MainActivityTest.java
index 34aa71a0159e123793bea6c4dda634924f1481af..405627048dfd0623b5fd610e3b7671bb155b673b 100644
--- a/app/src/androidTest/java/net/sourceforge/opencamera/test/MainActivityTest.java
+++ b/app/src/androidTest/java/net/sourceforge/opencamera/test/MainActivityTest.java
@@ -66,8 +66,6 @@ public class MainActivityTest extends ActivityInstrumentationTestCase2<MainActiv
     private static final String TAG = "MainActivityTest";
     private MainActivity mActivity = null;
     private Preview mPreview = null;
-    public static final boolean test_camera2 = false;
-    //public static final boolean test_camera2 = true;
 
     public MainActivityTest() {
         //noinspection deprecation
@@ -88,7 +86,7 @@ public class MainActivityTest extends ActivityInstrumentationTestCase2<MainActiv
         setActivityInitialTouchMode(false);
 
         // use getTargetContext() as we haven't started the activity yet (and don't want to, as we want to set prefs before starting)
-        TestUtils.initTest(this.getInstrumentation().getTargetContext(), test_camera2);
+        TestUtils.initTest(this.getInstrumentation().getTargetContext());
 
         Intent intent = createDefaultIntent();
         setActivityIntent(intent);
@@ -2401,8 +2399,8 @@ public class MainActivityTest extends ActivityInstrumentationTestCase2<MainActiv
         assertEquals(new_count_cameraContinuousFocusMoving, saved_count_cameraContinuousFocusMoving);
     }
 
-    /* Test for taking HDR photo then going to background, also tests notifications.
-     * Note test is unstable on Android emulator when testing for the notification, unclear why.
+    /* Test for taking HDR photo then going to background[, also tests notifications].
+     * [Note test is unstable on Android emulator when testing for the notification, unclear why.]
      */
     public void testPhotoBackgroundHDR() throws InterruptedException {
         Log.d(TAG, "testPhotoBackgroundHDR");
@@ -2442,7 +2440,7 @@ public class MainActivityTest extends ActivityInstrumentationTestCase2<MainActiv
 
         // go to background after a short pause
         Thread.sleep(500);
-        assertFalse(mActivity.testHasNotification());
+        //assertFalse(mActivity.testHasNotification());
         mActivity.runOnUiThread(new Runnable() {
             public void run() {
                 Log.d(TAG, "pause...");
@@ -2453,12 +2451,12 @@ public class MainActivityTest extends ActivityInstrumentationTestCase2<MainActiv
         this.getInstrumentation().waitForIdleSync();
 
         assertEquals(1, mPreview.count_cameraTakePicture);
-        if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.O ) {
+        /*if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.O ) {
             assertTrue(mActivity.testHasNotification());
-        }
+        }*/
         mActivity.waitUntilImageQueueEmpty();
         this.getInstrumentation().waitForIdleSync();
-        assertFalse(mActivity.testHasNotification());
+        //assertFalse(mActivity.testHasNotification());
 
         int n_new_files = getNFiles() - n_files;
         Log.d(TAG, "n_new_files: " + n_new_files);
@@ -3288,7 +3286,13 @@ public class MainActivityTest extends ActivityInstrumentationTestCase2<MainActiv
             Thread.sleep(100);
             Log.d(TAG, "about to click preview again for double tap");
             //TouchUtils.tapView(MainActivityTest.this, mPreview.getView());
-            mPreview.onDoubleTap(); // calling tapView twice doesn't seem to work consistently, so we call this directly!
+            mActivity.runOnUiThread(new Runnable() {
+                @Override
+                public void run() {
+                    mPreview.onDoubleTap(); // calling tapView twice doesn't seem to work consistently, so we call this directly!
+                }
+            });
+            // need to wait for UI code to finish before leaving
             this.getInstrumentation().waitForIdleSync();
         }
         if( wait_after_focus && !single_tap_photo && !double_tap_photo) {
@@ -10093,7 +10097,7 @@ public class MainActivityTest extends ActivityInstrumentationTestCase2<MainActiv
 
         setToDefault();
 
-        int display_orientation = mActivity.getApplicationInterface().getDisplayRotation();
+        int display_orientation = mActivity.getApplicationInterface().getDisplayRotation(true);
         Log.d(TAG, "display_orientation = " + display_orientation);
 
         SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(mActivity);
@@ -10102,7 +10106,7 @@ public class MainActivityTest extends ActivityInstrumentationTestCase2<MainActiv
         editor.apply();
         updateForSettings();
 
-        int new_display_orientation =  mActivity.getApplicationInterface().getDisplayRotation();
+        int new_display_orientation =  mActivity.getApplicationInterface().getDisplayRotation(true);
         Log.d(TAG, "new_display_orientation = " + new_display_orientation);
         assertEquals(new_display_orientation, ((display_orientation + 2) % 4));
     }
@@ -11312,12 +11316,20 @@ public class MainActivityTest extends ActivityInstrumentationTestCase2<MainActiv
             Thread.sleep(2000);
 
             assertTrue( mActivity.getApplicationInterface().getGyroSensor().isRecording() );
-            mActivity.getApplicationInterface().getGyroSensor().testForceTargetAchieved(0);
+            mActivity.runOnUiThread(new Runnable() {
+                @Override
+                public void run() {
+                    mActivity.getApplicationInterface().getGyroSensor().testForceTargetAchieved(0);
+                }
+            });
+            // need to wait for UI code to finish before leaving
+            this.getInstrumentation().waitForIdleSync();
             Log.d(TAG, "wait for taking photo");
             waitForTakePhoto();
             Log.d(TAG, "done taking photo");
             this.getInstrumentation().waitForIdleSync();
             Log.d(TAG, "after idle sync");
+            Log.d(TAG, "take picture count: " + mPreview.count_cameraTakePicture);
             assertEquals(mPreview.count_cameraTakePicture, i + 2);
         }
 
diff --git a/app/src/androidTest/java/net/sourceforge/opencamera/test/MainTests.java b/app/src/androidTest/java/net/sourceforge/opencamera/test/MainTests.java
index 782bebb9f8b691bf5364d5f5efc18abb6a141d23..52b7fdc9d19836ac240b85dbd62bdcf873a6b3ab 100644
--- a/app/src/androidTest/java/net/sourceforge/opencamera/test/MainTests.java
+++ b/app/src/androidTest/java/net/sourceforge/opencamera/test/MainTests.java
@@ -5,6 +5,8 @@ import android.os.Build;
 import junit.framework.Test;
 import junit.framework.TestSuite;
 
+import net.sourceforge.opencamera.TestUtils;
+
 public class MainTests {
     // Tests that don't fit into another of the Test suites
     public static Test suite() {
@@ -17,7 +19,7 @@ public class MainTests {
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testLocationSettings"));
         // other tests:
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testScopedStorageChecks1"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testScopedStorageChecks2"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testScopedStorageChecks3"));
         }
@@ -25,7 +27,7 @@ public class MainTests {
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testPause"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testImmediatelyQuit"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testStartCameraPreviewCount"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testCamera2PrefUpgrade"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testSaveModes"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testFlashVideoMode"));
@@ -37,7 +39,7 @@ public class MainTests {
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testPreviewSize"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testPreviewSizeWYSIWYG"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testResolutionMaxMP"));
-        if( MainActivityTest.test_camera2 ) {
+        if( TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testResolutionBurst"));
         }
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testAutoFocus"));
@@ -49,7 +51,7 @@ public class MainTests {
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testSwitchResolution"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testFaceDetection"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testFocusFlashAvailability"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testFocusSwitchVideoSwitchCameras"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testFocusRemainMacroSwitchCamera"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testFocusRemainMacroSwitchPhoto"));
@@ -65,12 +67,12 @@ public class MainTests {
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testZoom"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testZoomIdle"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testZoomSwitchCamera"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testSwitchCameraIdle"));
         }
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testSwitchCameraRepeat"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTouchFocusQuick"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testGallery"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testSettings"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testSettingsSaveLoad"));
@@ -85,15 +87,15 @@ public class MainTests {
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testLayoutNoLimitsStartup"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testCameraModes"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testFailOpenCamera"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testAudioControlIcon"));
         }
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testIconsAgainstCameras"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testOnError"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testGPSString"));
         }
-        if( MainActivityTest.test_camera2 ) {
+        if( TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testPreviewBitmap"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testVideoFPSHighSpeed"));
         }
diff --git a/app/src/androidTest/java/net/sourceforge/opencamera/test/PhotoTests.java b/app/src/androidTest/java/net/sourceforge/opencamera/test/PhotoTests.java
index 7f09028e0250a55cdc3ec33280d5feeb13026cec..37a51537bc1043d1078cf0ecd32d071fbf85b154 100644
--- a/app/src/androidTest/java/net/sourceforge/opencamera/test/PhotoTests.java
+++ b/app/src/androidTest/java/net/sourceforge/opencamera/test/PhotoTests.java
@@ -3,6 +3,8 @@ package net.sourceforge.opencamera.test;
 import junit.framework.Test;
 import junit.framework.TestSuite;
 
+import net.sourceforge.opencamera.TestUtils;
+
 public class PhotoTests {
     // Tests related to taking photos; note that tests to do with photo mode that don't take photos are still part of MainTests
     public static Test suite() {
@@ -13,7 +15,7 @@ public class PhotoTests {
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testLocationDirectionOn"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testLocationOff"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testLocationOnSAF"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testDirectionOn"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testDirectionOnSAF"));
         }
@@ -29,7 +31,7 @@ public class PhotoTests {
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoFlashAuto"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoFlashOn"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoFlashTorch"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoAudioButton"));
         }
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoNoAutofocus"));
@@ -57,7 +59,7 @@ public class PhotoTests {
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoSingleTap"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoDoubleTap"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoAlt"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTimerBackground"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTimerSettings"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTimerPopup"));
@@ -66,17 +68,17 @@ public class PhotoTests {
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testContinuousPicture1"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testContinuousPicture2"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testContinuousPictureFocusRepeat"));
-        if( MainActivityTest.test_camera2 ) {
+        if( TestUtils.test_camera2 ) {
             // test_wait_capture_result only relevant for Camera2 API
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testContinuousPictureFocusRepeatWaitCaptureResult"));
         }
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testKeyboardControls"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testPhotoStamp"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testPhotoStampSAF"));
         }
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoDRO"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoDROPhotoStamp"));
         }
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoHDR"));
@@ -87,13 +89,13 @@ public class PhotoTests {
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoHDRPhotoStamp"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoExpo"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoPanorama"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoPanoramaMax"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoPanoramaCancel"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakePhotoPanoramaCancelBySettings"));
         }
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testCreateSaveFolder1"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testCreateSaveFolder2"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testCreateSaveFolder3"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testCreateSaveFolder4"));
diff --git a/app/src/androidTest/java/net/sourceforge/opencamera/test/VideoTests.java b/app/src/androidTest/java/net/sourceforge/opencamera/test/VideoTests.java
index 38b1f38cdc52886dcffc351b1a2e10538f03025f..471aff400db0b4f7f97fdd24a0b21d74921b7fd3 100644
--- a/app/src/androidTest/java/net/sourceforge/opencamera/test/VideoTests.java
+++ b/app/src/androidTest/java/net/sourceforge/opencamera/test/VideoTests.java
@@ -3,22 +3,24 @@ package net.sourceforge.opencamera.test;
 import junit.framework.Test;
 import junit.framework.TestSuite;
 
+import net.sourceforge.opencamera.TestUtils;
+
 public class VideoTests {
     // Tests related to video recording; note that tests to do with video mode that don't record are still part of MainTests
     public static Test suite() {
         TestSuite suite = new TestSuite(MainTests.class.getName());
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideo"));
         // put these tests first as they require various permissions be allowed, that can only be set by user action:
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoAudioControl"));
         }
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoSAF"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoSubtitles"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoSubtitlesSAF"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoSubtitlesGPSSAF"));
         }
-        if( MainActivityTest.test_camera2 ) {
+        if( TestUtils.test_camera2 ) {
             // tests for video log profile (but these don't actually record video)
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testLogProfile1"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testLogProfile2"));
@@ -37,7 +39,7 @@ public class VideoTests {
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoFocusArea"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoQuick"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoQuickSAF"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoMaxDuration"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoMaxDurationRestart"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoMaxDurationRestartInterrupt"));
@@ -50,18 +52,18 @@ public class VideoTests {
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoSnapshotTimer"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoSnapshotPausePreview"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoSnapshotMax"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoFlashVideo"));
         }
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testVideoTimerInterrupt"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testVideoPopup"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testVideoTimerPopup"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoAvailableMemory"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoAvailableMemory2"));
         }
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoMaxFileSize1"));
-        if( !MainActivityTest.test_camera2 ) {
+        if( !TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoMaxFileSize2"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoMaxFileSize3"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoMaxFileSize4"));
@@ -72,7 +74,7 @@ public class VideoTests {
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoForceFailureSAF"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoForceIOException"));
         suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoForceCameraControllerException"));
-        if( MainActivityTest.test_camera2 ) {
+        if( TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testVideoLogProfile"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testVideoJTLogProfile"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testVideoGammaProfile"));
@@ -80,7 +82,7 @@ public class VideoTests {
         }
         // put tests which change bitrate, fps or test 4K at end
         //suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoFPS")); // disabled as unreliable
-        if( MainActivityTest.test_camera2 ) {
+        if( TestUtils.test_camera2 ) {
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoFPSHighSpeedManual"));
             suite.addTest(TestSuite.createTest(MainActivityTest.class, "testTakeVideoSlowMotion"));
         }
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index b8fdfc42aed203a11b2d0b8237d36140e4447484..75a70dc68a50ab674f52fe955a747201371bf138 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -1,8 +1,8 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
-    android:versionCode="87"
-    android:versionName="1.51.1"
+    android:versionCode="88"
+    android:versionName="1.52"
     android:installLocation="auto"
     tools:ignore="GoogleAppIndexingWarning">
     <!-- ignore GoogleAppIndexingWarning as we don't want to implement that -->
diff --git a/app/src/main/java/net/sourceforge/opencamera/HDRProcessor.java b/app/src/main/java/net/sourceforge/opencamera/HDRProcessor.java
index 5a187a7b7f9f0adc7d00166f60d3b6cb0f43d136..a1c93795e0d19556352886b862ebc8d003381442 100644
--- a/app/src/main/java/net/sourceforge/opencamera/HDRProcessor.java
+++ b/app/src/main/java/net/sourceforge/opencamera/HDRProcessor.java
@@ -595,6 +595,11 @@ public class HDRProcessor {
                 float this_B = response_functions[i].parameter_B;
                 response_functions[i].parameter_A = this_A / a;
                 response_functions[i].parameter_B = this_B - this_A * b / a;
+                if( response_functions[i].parameter_B < 1.0e-5f ) {
+                    if( MyDebug.LOG )
+                        Log.e(TAG, "remapped parameter B too small or negative: " + response_functions[i].parameter_B);
+                    response_functions[i].parameter_B = 1.0e-5f;
+                }
                 if( MyDebug.LOG ) {
                     Log.d(TAG, "remapped: " + i);
                     Log.d(TAG, "    A: " + this_A + " -> " + response_functions[i].parameter_A);
@@ -637,108 +642,6 @@ public class HDRProcessor {
 
         // write new hdr image
 
-        // create RenderScript
-        /*if( processHDRScript == null ) {
-            processHDRScript = new ScriptC_process_hdr(rs);
-        }*/
-        ScriptC_process_hdr processHDRScript = new ScriptC_process_hdr(rs);
-
-        // set allocations
-        processHDRScript.set_bitmap0(allocations[0]);
-        if( n_bitmaps > 2 ) {
-            processHDRScript.set_bitmap2(allocations[2]);
-        }
-
-        // set offsets
-        processHDRScript.set_offset_x0(offsets_x[0]);
-        processHDRScript.set_offset_y0(offsets_y[0]);
-        // no offset for middle image
-        if( n_bitmaps > 2 ) {
-            processHDRScript.set_offset_x2(offsets_x[2]);
-            processHDRScript.set_offset_y2(offsets_y[2]);
-        }
-
-        // set response functions
-        processHDRScript.set_parameter_A0(response_functions[0].parameter_A);
-        processHDRScript.set_parameter_B0(response_functions[0].parameter_B);
-        // no response function for middle image
-        if( n_bitmaps > 2 ) {
-            processHDRScript.set_parameter_A2(response_functions[2].parameter_A);
-            processHDRScript.set_parameter_B2(response_functions[2].parameter_B);
-        }
-
-        if( use_hdr_n ) {
-            // now need to set values for image 1
-            processHDRScript.set_bitmap1(allocations[1]);
-            processHDRScript.set_offset_x1(offsets_x[1]);
-            processHDRScript.set_offset_y1(offsets_y[1]);
-            processHDRScript.set_parameter_A1(response_functions[1].parameter_A);
-            processHDRScript.set_parameter_B1(response_functions[1].parameter_B);
-        }
-
-        if( n_bitmaps > 3 ) {
-            processHDRScript.set_bitmap3(allocations[3]);
-            processHDRScript.set_offset_x3(offsets_x[3]);
-            processHDRScript.set_offset_y3(offsets_y[3]);
-            processHDRScript.set_parameter_A3(response_functions[3].parameter_A);
-            processHDRScript.set_parameter_B3(response_functions[3].parameter_B);
-
-            if( n_bitmaps > 4 ) {
-                processHDRScript.set_bitmap4(allocations[4]);
-                processHDRScript.set_offset_x4(offsets_x[4]);
-                processHDRScript.set_offset_y4(offsets_y[4]);
-                processHDRScript.set_parameter_A4(response_functions[4].parameter_A);
-                processHDRScript.set_parameter_B4(response_functions[4].parameter_B);
-
-                if( n_bitmaps > 5 ) {
-                    processHDRScript.set_bitmap5(allocations[5]);
-                    processHDRScript.set_offset_x5(offsets_x[5]);
-                    processHDRScript.set_offset_y5(offsets_y[5]);
-                    processHDRScript.set_parameter_A5(response_functions[5].parameter_A);
-                    processHDRScript.set_parameter_B5(response_functions[5].parameter_B);
-
-                    if( n_bitmaps > 6 ) {
-                        processHDRScript.set_bitmap6(allocations[6]);
-                        processHDRScript.set_offset_x6(offsets_x[6]);
-                        processHDRScript.set_offset_y6(offsets_y[6]);
-                        processHDRScript.set_parameter_A6(response_functions[6].parameter_A);
-                        processHDRScript.set_parameter_B6(response_functions[6].parameter_B);
-                    }
-                }
-            }
-        }
-
-        // set globals
-
-        // set tonemapping algorithm
-        switch( tonemapping_algorithm ) {
-            case TONEMAPALGORITHM_CLAMP:
-                if( MyDebug.LOG )
-                    Log.d(TAG, "tonemapping algorithm: clamp");
-                processHDRScript.set_tonemap_algorithm( processHDRScript.get_tonemap_algorithm_clamp_c() );
-                break;
-            case TONEMAPALGORITHM_EXPONENTIAL:
-                if( MyDebug.LOG )
-                    Log.d(TAG, "tonemapping algorithm: exponential");
-                processHDRScript.set_tonemap_algorithm( processHDRScript.get_tonemap_algorithm_exponential_c() );
-                break;
-            case TONEMAPALGORITHM_REINHARD:
-                if( MyDebug.LOG )
-                    Log.d(TAG, "tonemapping algorithm: reinhard");
-                processHDRScript.set_tonemap_algorithm( processHDRScript.get_tonemap_algorithm_reinhard_c() );
-                break;
-            case TONEMAPALGORITHM_FU2:
-                if( MyDebug.LOG )
-                    Log.d(TAG, "tonemapping algorithm: fu2");
-                processHDRScript.set_tonemap_algorithm( processHDRScript.get_tonemap_algorithm_fu2_c() );
-                break;
-            case TONEMAPALGORITHM_ACES:
-                if( MyDebug.LOG )
-                    Log.d(TAG, "tonemapping algorithm: aces");
-                processHDRScript.set_tonemap_algorithm( processHDRScript.get_tonemap_algorithm_aces_c() );
-                break;
-        }
-
         float max_possible_value = response_functions[0].parameter_A * 255 + response_functions[0].parameter_B;
         //float max_possible_value = response_functions[base_bitmap - 1].parameter_A * 255 + response_functions[base_bitmap - 1].parameter_B;
         if( MyDebug.LOG )
@@ -806,9 +709,10 @@ public class HDRProcessor {
         // (tonemap_scale_c==255 means therefore that colours will only be made darker).
         if( MyDebug.LOG )
             Log.d(TAG, "tonemap_scale_c: " + tonemap_scale_c);
-        processHDRScript.set_tonemap_scale(tonemap_scale_c);
 
         // algorithm specific parameters
+        float linear_scale = 0.0f;
+        float W = 0.0f;
         switch( tonemapping_algorithm ) {
             case TONEMAPALGORITHM_EXPONENTIAL:
             {
@@ -819,11 +723,10 @@ public class HDRProcessor {
                 // so 1 = S . (1 - exp( - E * Vmax ))
                 // => S = 1 / (1 - exp( - E * Vmax ))
                 // Note that Vmax should be set to a minimum of 255, else we'll make darker images brighter.
-                float E = processHDRScript.get_exposure();
-                float linear_scale = (float)(1.0 / (1.0 - Math.exp(-E * max_possible_value / 255.0)));
+                final float exposure = 1.2f; // should match setting in process_hdr.rs
+                linear_scale = (float)(1.0 / (1.0 - Math.exp(-exposure * max_possible_value / 255.0)));
                 if( MyDebug.LOG )
                     Log.d(TAG, "linear_scale: " + linear_scale);
-                processHDRScript.set_linear_scale(linear_scale);
                 break;
             }
             case TONEMAPALGORITHM_REINHARD: {
@@ -846,20 +749,135 @@ public class HDRProcessor {
                 // max_possible_value >= 255.
                 // Note that the original Reinhard tonemapping paper describes a non-linear scaling by (1 + CV/Vmax^2),
                 // though this is poorer performance (in terms of calculation time).
-                float linear_scale = (max_possible_value + tonemap_scale_c) / max_possible_value;
+                linear_scale = (max_possible_value + tonemap_scale_c) / max_possible_value;
                 if( MyDebug.LOG )
                     Log.d(TAG, "linear_scale: " + linear_scale);
-                processHDRScript.set_linear_scale(linear_scale);
                 break;
             }
             case TONEMAPALGORITHM_FU2:
             {
                 // For FU2, we have f(V) = U(EV) / U(W), where V is the HDR value, U is a function.
                 // We want f(Vmax) = 1, so EVmax = W
-                float E = processHDRScript.get_fu2_exposure_bias();
-                float W = E * max_possible_value;
+                final float fu2_exposure_bias = 2.0f / 255.0f; // should match setting in process_hdr.rs
+                W = fu2_exposure_bias * max_possible_value;
                 if( MyDebug.LOG )
                     Log.d(TAG, "fu2 W: " + W);
+                break;
+            }
+        }
+
+        // create RenderScript
+        /*if( processHDRScript == null ) {
+            processHDRScript = new ScriptC_process_hdr(rs);
+        }*/
+        ScriptC_process_hdr processHDRScript = new ScriptC_process_hdr(rs);
+
+        // set allocations
+        processHDRScript.set_bitmap0(allocations[0]);
+        if( n_bitmaps > 2 ) {
+            processHDRScript.set_bitmap2(allocations[2]);
+        }
+
+        // set offsets
+        processHDRScript.set_offset_x0(offsets_x[0]);
+        processHDRScript.set_offset_y0(offsets_y[0]);
+        // no offset for middle image
+        if( n_bitmaps > 2 ) {
+            processHDRScript.set_offset_x2(offsets_x[2]);
+            processHDRScript.set_offset_y2(offsets_y[2]);
+        }
+
+        // set response functions
+        processHDRScript.set_parameter_A0(response_functions[0].parameter_A);
+        processHDRScript.set_parameter_B0(response_functions[0].parameter_B);
+        // no response function for middle image
+        if( n_bitmaps > 2 ) {
+            processHDRScript.set_parameter_A2(response_functions[2].parameter_A);
+            processHDRScript.set_parameter_B2(response_functions[2].parameter_B);
+        }
+
+        if( use_hdr_n ) {
+            // now need to set values for image 1
+            processHDRScript.set_bitmap1(allocations[1]);
+            processHDRScript.set_offset_x1(offsets_x[1]);
+            processHDRScript.set_offset_y1(offsets_y[1]);
+            processHDRScript.set_parameter_A1(response_functions[1].parameter_A);
+            processHDRScript.set_parameter_B1(response_functions[1].parameter_B);
+        }
+
+        if( n_bitmaps > 3 ) {
+            processHDRScript.set_bitmap3(allocations[3]);
+            processHDRScript.set_offset_x3(offsets_x[3]);
+            processHDRScript.set_offset_y3(offsets_y[3]);
+            processHDRScript.set_parameter_A3(response_functions[3].parameter_A);
+            processHDRScript.set_parameter_B3(response_functions[3].parameter_B);
+
+            if( n_bitmaps > 4 ) {
+                processHDRScript.set_bitmap4(allocations[4]);
+                processHDRScript.set_offset_x4(offsets_x[4]);
+                processHDRScript.set_offset_y4(offsets_y[4]);
+                processHDRScript.set_parameter_A4(response_functions[4].parameter_A);
+                processHDRScript.set_parameter_B4(response_functions[4].parameter_B);
+
+                if( n_bitmaps > 5 ) {
+                    processHDRScript.set_bitmap5(allocations[5]);
+                    processHDRScript.set_offset_x5(offsets_x[5]);
+                    processHDRScript.set_offset_y5(offsets_y[5]);
+                    processHDRScript.set_parameter_A5(response_functions[5].parameter_A);
+                    processHDRScript.set_parameter_B5(response_functions[5].parameter_B);
+
+                    if( n_bitmaps > 6 ) {
+                        processHDRScript.set_bitmap6(allocations[6]);
+                        processHDRScript.set_offset_x6(offsets_x[6]);
+                        processHDRScript.set_offset_y6(offsets_y[6]);
+                        processHDRScript.set_parameter_A6(response_functions[6].parameter_A);
+                        processHDRScript.set_parameter_B6(response_functions[6].parameter_B);
+                    }
+                }
+            }
+        }
+
+        // set globals
+
+        // set tonemapping algorithm
+        switch( tonemapping_algorithm ) {
+            case TONEMAPALGORITHM_CLAMP:
+                if( MyDebug.LOG )
+                    Log.d(TAG, "tonemapping algorithm: clamp");
+                processHDRScript.set_tonemap_algorithm( processHDRScript.get_tonemap_algorithm_clamp_c() );
+                break;
+            case TONEMAPALGORITHM_EXPONENTIAL:
+                if( MyDebug.LOG )
+                    Log.d(TAG, "tonemapping algorithm: exponential");
+                processHDRScript.set_tonemap_algorithm( processHDRScript.get_tonemap_algorithm_exponential_c() );
+                break;
+            case TONEMAPALGORITHM_REINHARD:
+                if( MyDebug.LOG )
+                    Log.d(TAG, "tonemapping algorithm: reinhard");
+                processHDRScript.set_tonemap_algorithm( processHDRScript.get_tonemap_algorithm_reinhard_c() );
+                break;
+            case TONEMAPALGORITHM_FU2:
+                if( MyDebug.LOG )
+                    Log.d(TAG, "tonemapping algorithm: fu2");
+                processHDRScript.set_tonemap_algorithm( processHDRScript.get_tonemap_algorithm_fu2_c() );
+                break;
+            case TONEMAPALGORITHM_ACES:
+                if( MyDebug.LOG )
+                    Log.d(TAG, "tonemapping algorithm: aces");
+                processHDRScript.set_tonemap_algorithm( processHDRScript.get_tonemap_algorithm_aces_c() );
+                break;
+        }
+
+        processHDRScript.set_tonemap_scale(tonemap_scale_c);
+
+        // set algorithm specific parameters
+        switch( tonemapping_algorithm ) {
+            case TONEMAPALGORITHM_EXPONENTIAL:
+            case TONEMAPALGORITHM_REINHARD:
+                processHDRScript.set_linear_scale(linear_scale);
+                break;
+            case TONEMAPALGORITHM_FU2:
+            {
                 processHDRScript.set_W(W);
                 break;
             }
@@ -867,12 +885,14 @@ public class HDRProcessor {
 
         if( MyDebug.LOG )
             Log.d(TAG, "call processHDRScript");
-        Allocation output_allocation;
+        final Allocation output_allocation;
         boolean free_output_allocation = false;
         if( release_bitmaps ) {
             // must use allocations[base_bitmap] as the output, as that's the image guaranteed to have no offset (otherwise we'll have
             // problems due to the output being equal to one of the inputs)
             output_allocation = allocations[base_bitmap];
+            // similarly must be the base_bitmap we copy to
+            output_bitmap = bitmaps.get(base_bitmap);
         }
         else {
             output_allocation = Allocation.createFromBitmap(rs, output_bitmap);
@@ -905,31 +925,26 @@ public class HDRProcessor {
         }
 
         if( hdr_alpha != 0.0f ) {
-            adjustHistogram(output_allocation, output_allocation, width, height, hdr_alpha, n_tiles, ce_preserve_blacks, time_s);
+            adjustHistogramRS(output_allocation, output_allocation, width, height, hdr_alpha, n_tiles, ce_preserve_blacks, time_s);
             if( MyDebug.LOG )
                 Log.d(TAG, "### time after adjustHistogram: " + (System.currentTimeMillis() - time_s));
         }
 
-        if( release_bitmaps ) {
-            // must be the base_bitmap we copy to - see note above about using allocations[base_bitmap] as the output
-            allocations[base_bitmap].copyTo(bitmaps.get(base_bitmap));
-            if( MyDebug.LOG )
-                Log.d(TAG, "### time after copying to bitmap: " + (System.currentTimeMillis() - time_s));
+        output_allocation.copyTo(output_bitmap);
+        if( MyDebug.LOG )
+            Log.d(TAG, "### time after copying to bitmap: " + (System.currentTimeMillis() - time_s));
+
+        if( free_output_allocation )
+            output_allocation.destroy();
 
+        if( release_bitmaps ) {
             // make it so that we store the output bitmap as first in the list
-            bitmaps.set(0, bitmaps.get(base_bitmap));
+            bitmaps.set(0, output_bitmap);
             for(int i=1;i<bitmaps.size();i++) {
                 bitmaps.set(i, null);
             }
         }
-        else {
-            output_allocation.copyTo(output_bitmap);
-            if( MyDebug.LOG )
-                Log.d(TAG, "### time after copying to bitmap: " + (System.currentTimeMillis() - time_s));
-        }
 
-        if( free_output_allocation )
-            output_allocation.destroy();
         for(int i=0;i<n_bitmaps;i++) {
             allocations[i].destroy();
             allocations[i] = null;
@@ -951,7 +966,7 @@ public class HDRProcessor {
 
         initRenderscript();
         if( MyDebug.LOG )
-            Log.d(TAG, "### time after creating renderscript: " + (System.currentTimeMillis() - time_s));
+            Log.d(TAG, "### processSingleImage: time after creating renderscript: " + (System.currentTimeMillis() - time_s));
 
         // create allocation
         Allocation allocation = Allocation.createFromBitmap(rs, bitmaps.get(0));
@@ -960,6 +975,7 @@ public class HDRProcessor {
         boolean free_output_allocation = false;
         if( release_bitmaps ) {
             output_allocation = allocation;
+            output_bitmap = bitmaps.get(0);
         }
         else {
             free_output_allocation = true;
@@ -968,12 +984,12 @@ public class HDRProcessor {
 
         if( dro_tonemapping_algorithm == DROTonemappingAlgorithm.DROALGORITHM_GAINGAMMA ) {
             // brighten?
-            int [] histo = computeHistogram(allocation, false, false);
+            int [] histo = computeHistogram(allocation, width, height, false, false);
             HistogramInfo histogramInfo = getHistogramInfo(histo);
             int brightness = histogramInfo.median_brightness;
             int max_brightness = histogramInfo.max_brightness;
             if( MyDebug.LOG )
-                Log.d(TAG, "### time after computeHistogram: " + (System.currentTimeMillis() - time_s));
+                Log.d(TAG, "### processSingleImage: time after computeHistogram: " + (System.currentTimeMillis() - time_s));
             if( MyDebug.LOG ) {
                 Log.d(TAG, "median brightness: " + brightness);
                 Log.d(TAG, "max brightness: " + max_brightness);
@@ -1008,20 +1024,15 @@ public class HDRProcessor {
                 }
                 allocation = output_allocation;
                 if( MyDebug.LOG )
-                    Log.d(TAG, "### time after dro_brighten: " + (System.currentTimeMillis() - time_s));
+                    Log.d(TAG, "### processSingleImage: time after dro_brighten: " + (System.currentTimeMillis() - time_s));
             }
         }
 
-        adjustHistogram(allocation, output_allocation, width, height, hdr_alpha, n_tiles, ce_preserve_blacks, time_s);
+        adjustHistogramRS(allocation, output_allocation, width, height, hdr_alpha, n_tiles, ce_preserve_blacks, time_s);
 
-        if( release_bitmaps ) {
-            allocation.copyTo(bitmaps.get(0));
-        }
-        else {
-            output_allocation.copyTo(output_bitmap);
-        }
+        output_allocation.copyTo(output_bitmap);
         if( MyDebug.LOG )
-            Log.d(TAG, "time after copying to bitmap: " + (System.currentTimeMillis() - time_s));
+            Log.d(TAG, "### processSingleImage: time after copying to bitmap: " + (System.currentTimeMillis() - time_s));
 
         if( free_output_allocation )
             allocation.destroy();
@@ -1029,7 +1040,7 @@ public class HDRProcessor {
         freeScripts();
 
         if( MyDebug.LOG )
-            Log.d(TAG, "time for processSingleImage: " + (System.currentTimeMillis() - time_s));
+            Log.d(TAG, "### time for processSingleImage: " + (System.currentTimeMillis() - time_s));
     }
 
     void brightenImage(Bitmap bitmap, int brightness, int max_brightness, int brightness_target) {
@@ -1230,7 +1241,7 @@ public class HDRProcessor {
         if( MyDebug.LOG )
             Log.d(TAG, "median: " + luminanceInfo.median_value);*/
 
-        AvgData avg_data = processAvgCore(null, null, bitmap_avg, bitmap_new, width, height, avg_factor, iso, exposure_time, zoom_factor, null, null, null, time_s);
+        AvgData avg_data = processAvgCore(null, bitmap_avg, bitmap_new, width, height, avg_factor, iso, exposure_time, zoom_factor, time_s);
 
         //allocation_avg.copyTo(bitmap_avg);
 
@@ -1271,62 +1282,80 @@ public class HDRProcessor {
         if( MyDebug.LOG )
             Log.d(TAG, "### time after creating allocations from bitmaps: " + (System.currentTimeMillis() - time_s));*/
 
-        processAvgCore(avg_data.allocation_out, avg_data.allocation_out, null, bitmap_new, width, height, avg_factor, iso, exposure_time, zoom_factor, avg_data.allocation_avg_align, avg_data.bitmap_avg_align, avg_data.allocation_orig, time_s);
+        processAvgCore(avg_data, null, bitmap_new, width, height, avg_factor, iso, exposure_time, zoom_factor, time_s);
 
         if( MyDebug.LOG )
             Log.d(TAG, "### time for updateAvg: " + (System.currentTimeMillis() - time_s));
     }
 
     /** Core algorithm for Noise Reduction algorithm.
-     * @param allocation_out If non-null, this will be used for the output allocation, otherwise a
-     *                       new one will be created.
-     * @param allocation_avg If non-null, an allocation for the averaged image so far. If null, the
-     *                       first bitmap should be supplied as bitmap_avg.
+     * @param avg_data       Should be null for first call, and non-null for subsequent calls. This should
+     *                       be the AvgData returned by the first call.
      * @param bitmap_avg     If non-null, the first bitmap (which will be recycled when the returned
-     *                       AvgData is destroyed). If null, an allocation_avg should be supplied.
+     *                       AvgData is destroyed). If null, an avg_data should be supplied.
      * @param bitmap_new     The new bitmap to combined. The bitmap will be recycled.
      * @param width          The width of the bitmaps.
      * @param height         The height of the bitmaps.
      * @param avg_factor     The averaging factor.
      * @param iso            The ISO used for the photos.
      * @param zoom_factor    The digital zoom factor used to take the photos.
-     * @param allocation_avg_align If non-null, use this allocation for alignment for averaged image.
-     * @param bitmap_avg_align Should be supplied if allocation_avg_align is non-null, and stores
-     *                         the bitmap corresponding to the allocation_avg_align.
-     * @param allocation_orig
-     *                       If non-null, this is an allocation representing the first image.
      * @param time_s         Time, for debugging.
      */
     @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
-    private AvgData processAvgCore(Allocation allocation_out, Allocation allocation_avg, Bitmap bitmap_avg, Bitmap bitmap_new, int width, int height, float avg_factor, int iso, long exposure_time, float zoom_factor, Allocation allocation_avg_align, Bitmap bitmap_avg_align, Allocation allocation_orig, long time_s) {
+    private AvgData processAvgCore(AvgData avg_data, Bitmap bitmap_avg, Bitmap bitmap_new, int width, int height, float avg_factor, int iso, long exposure_time, float zoom_factor, long time_s) {
         if( MyDebug.LOG ) {
             Log.d(TAG, "processAvgCore");
             Log.d(TAG, "iso: " + iso);
             Log.d(TAG, "zoom_factor: " + zoom_factor);
         }
 
-        Allocation allocation_new = null;
-        boolean free_allocation_avg = false;
+        // If non-null, allocation_out is an allocation of the averaged image so far, and it will
+        // also be used for the output allocation. If null, the first bitmap should be supplied as
+        // bitmap_avg, and a new allocation will be created for the output.
+        Allocation allocation_out = null;
+        Bitmap bitmap_avg_align = null; // if non-null, use this bitmap for alignment for averaged image.
+        Allocation allocation_avg_align = null; // allocation corresponding to bitmap_avg_align
+        Bitmap bitmap_orig = null; // if non-null, this is a bitmap representing the first image.
+        Allocation allocation_orig = null; // allocation corresponding to bitmap_orig
+        if( avg_data != null ) {
+            allocation_out = avg_data.allocation_out;
+            bitmap_avg_align = avg_data.bitmap_avg_align;
+            allocation_avg_align = avg_data.allocation_avg_align;
+            bitmap_orig = avg_data.bitmap_orig;
+            allocation_orig = avg_data.allocation_orig;
+        }
 
         //Allocation allocation_diffs = null;
 
         offsets_x = new int[2];
         offsets_y = new int[2];
-        boolean floating_point = bitmap_avg == null;
+        boolean floating_point;
+        if( bitmap_avg != null && allocation_out == null ) {
+            if( MyDebug.LOG )
+                Log.d(TAG, "process first bitmap");
+            floating_point = false;
+        }
+        else if( bitmap_avg == null && allocation_out != null ) {
+            floating_point = true;
+            if( MyDebug.LOG )
+                Log.d(TAG, "processing existing allocation");
+        }
+        else {
+            throw new RuntimeException("only one of bitmap_avg or allocation_out should be supplied");
+        }
+
         {
-            boolean floating_point_align = floating_point;
+            boolean floating_point_align;
             // perform auto-alignment
             List<Bitmap> align_bitmaps = new ArrayList<>();
             Allocation [] allocations = new Allocation[2];
-            Bitmap bitmap_new_align = null;
-            Allocation allocation_new_align = null;
-            int alignment_width = width;
-            int alignment_height = height;
+            Bitmap bitmap_new_align;
+            Allocation allocation_new_align;
+            int alignment_width;
+            int alignment_height;
             int full_alignment_width = width;
             int full_alignment_height = height;
 
-            //final boolean scale_align = false;
-            final boolean scale_align = true;
             //final int scale_align_size = 2;
             //final int scale_align_size = 4;
             //final int scale_align_size = Math.max(4 / this.cached_avg_sample_size, 1);
@@ -1336,7 +1365,7 @@ public class HDRProcessor {
             if( MyDebug.LOG )
                 Log.d(TAG, "scale_align_size: " + scale_align_size);
             boolean crop_to_centre = true;
-            if( scale_align ) {
+            {
                 // use scaled down and/or cropped bitmaps for alignment
                 if( MyDebug.LOG )
                     Log.d(TAG, "### time before creating allocations for autoalignment: " + (System.currentTimeMillis() - time_s));
@@ -1364,11 +1393,11 @@ public class HDRProcessor {
 
                 final boolean filter_align = false;
                 //final boolean filter_align = true;
-                if( allocation_avg_align == null ) {
+                if( bitmap_avg_align == null ) {
                     bitmap_avg_align = Bitmap.createBitmap(bitmap_avg, align_x, align_y, align_width, align_height, align_scale_matrix, filter_align);
                     allocation_avg_align = Allocation.createFromBitmap(rs, bitmap_avg_align);
                     if( MyDebug.LOG )
-                        Log.d(TAG, "### time after creating avg allocation for autoalignment: " + (System.currentTimeMillis() - time_s));
+                        Log.d(TAG, "### time after creating avg bitmap for autoalignment: " + (System.currentTimeMillis() - time_s));
                 }
                 bitmap_new_align = Bitmap.createBitmap(bitmap_new, align_x, align_y, align_width, align_height, align_scale_matrix, filter_align);
                 allocation_new_align = Allocation.createFromBitmap(rs, bitmap_new_align);
@@ -1384,19 +1413,6 @@ public class HDRProcessor {
                 if( MyDebug.LOG )
                     Log.d(TAG, "### time after creating allocations for autoalignment: " + (System.currentTimeMillis() - time_s));
             }
-            else {
-                if( allocation_avg == null ) {
-                    allocation_avg = Allocation.createFromBitmap(rs, bitmap_avg);
-                    free_allocation_avg = true;
-                }
-                allocation_new = Allocation.createFromBitmap(rs, bitmap_new);
-                if( MyDebug.LOG )
-                    Log.d(TAG, "### time after creating allocations from bitmaps: " + (System.currentTimeMillis() - time_s));
-                align_bitmaps.add(bitmap_avg);
-                align_bitmaps.add(bitmap_new);
-                allocations[0] = allocation_avg;
-                allocations[1] = allocation_new;
-            }
 
             // misalignment more likely in "dark" images with more images and/or longer exposures
             // using max_align_scale=2 needed to prevent misalignment in testAvg51; also helps testAvg14
@@ -1420,7 +1436,7 @@ public class HDRProcessor {
             processAvgScript.set_allocation_diffs(allocation_diffs);
             */
 
-            if( scale_align ) {
+            {
                 for(int i=0;i<offsets_x.length;i++) {
                     offsets_x[i] *= scale_align_size;
                 }
@@ -1445,6 +1461,49 @@ public class HDRProcessor {
             }
         }
 
+        // write new avg image
+
+        // higher wiener_C (and higher wiener_cutoff_factor) means more averaging (but more risk of ghosting)
+        // if changing this, pay close attention to tests testAvg6, testAvg8, testAvg17, testAvg23
+        float limited_iso = Math.min(iso, 400);
+        float wiener_cutoff_factor = 1.0f;
+        if( iso >= 700 ) {
+            // helps reduce speckles in testAvg17, testAvg23, testAvg33, testAvg36, testAvg38
+            // using this level for testAvg31 (ISO 609) would increase ghosting
+            //limited_iso = 500;
+            limited_iso = 800;
+            if( iso >= 1100 ) {
+                // helps further reduce speckles in testAvg17, testAvg38
+                // but don't do for iso >= 700 as makes "vicks" text in testAvg23 slightly more blurred
+                wiener_cutoff_factor = 8.0f;
+            }
+        }
+        limited_iso = Math.max(limited_iso, 100);
+        float wiener_C = 10.0f * limited_iso;
+        //float wiener_C = 1000.0f;
+        //float wiener_C = 4000.0f;
+
+        // Tapering the wiener scale means that we do more averaging for earlier images in the stack, the
+        // logic being we'll have more chance of ghosting or misalignment with later images.
+        // This helps: testAvg31, testAvg33.
+        // Also slightly helps testAvg17, testAvg23 (slightly less white speckle on tv), testAvg28
+        // (one less white speckle on face).
+        // Note that too much tapering risks increasing ghosting in testAvg26, testAvg39.
+        float tapered_wiener_scale = 1.0f - (float)Math.pow(0.5, avg_factor);
+        if( MyDebug.LOG ) {
+            Log.d(TAG, "avg_factor: " + avg_factor);
+            Log.d(TAG, "tapered_wiener_scale: " + tapered_wiener_scale);
+        }
+        wiener_C /= tapered_wiener_scale;
+
+        float wiener_C_cutoff = wiener_cutoff_factor * wiener_C;
+        if( MyDebug.LOG ) {
+            Log.d(TAG, "wiener_C: " + wiener_C);
+            Log.d(TAG, "wiener_cutoff_factor: " + wiener_cutoff_factor);
+        }
+
+        Allocation allocation_avg = allocation_out;
+
         if( allocation_out == null ) {
             if( MyDebug.LOG )
                 Log.d(TAG, "need to create allocation_out");
@@ -1452,6 +1511,8 @@ public class HDRProcessor {
             if( MyDebug.LOG )
                 Log.d(TAG, "### time after create allocation_out: " + (System.currentTimeMillis() - time_s));
         }
+
+        boolean free_allocation_avg = false;
         if( allocation_avg == null ) {
             allocation_avg = Allocation.createFromBitmap(rs, bitmap_avg);
             free_allocation_avg = true;
@@ -1459,8 +1520,6 @@ public class HDRProcessor {
                 Log.d(TAG, "### time after creating allocation_avg from bitmap: " + (System.currentTimeMillis() - time_s));
         }
 
-        // write new avg image
-
         // create RenderScript
         if( processAvgScript == null ) {
             processAvgScript = new ScriptC_process_avg(rs);
@@ -1486,11 +1545,9 @@ public class HDRProcessor {
             first = false;
         }*/
 
-        if( allocation_new == null ) {
-            allocation_new = Allocation.createFromBitmap(rs, bitmap_new);
-            if( MyDebug.LOG )
-                Log.d(TAG, "### time after creating allocation_new from bitmap: " + (System.currentTimeMillis() - time_s));
-        }
+        Allocation allocation_new = Allocation.createFromBitmap(rs, bitmap_new);
+        if( MyDebug.LOG )
+            Log.d(TAG, "### time after creating allocation_new from bitmap: " + (System.currentTimeMillis() - time_s));
 
         // set allocations
 
@@ -1517,45 +1574,6 @@ public class HDRProcessor {
         // set globals
 
         processAvgScript.set_avg_factor(avg_factor);
-
-        // higher wiener_C (and higher wiener_cutoff_factor) means more averaging (but more risk of ghosting)
-        // if changing this, pay close attention to tests testAvg6, testAvg8, testAvg17, testAvg23
-        float limited_iso = Math.min(iso, 400);
-        float wiener_cutoff_factor = 1.0f;
-        if( iso >= 700 ) {
-            // helps reduce speckles in testAvg17, testAvg23, testAvg33, testAvg36, testAvg38
-            // using this level for testAvg31 (ISO 609) would increase ghosting
-            //limited_iso = 500;
-            limited_iso = 800;
-            if( iso >= 1100 ) {
-                // helps further reduce speckles in testAvg17, testAvg38
-                // but don't do for iso >= 700 as makes "vicks" text in testAvg23 slightly more blurred
-                wiener_cutoff_factor = 8.0f;
-            }
-        }
-        limited_iso = Math.max(limited_iso, 100);
-        float wiener_C = 10.0f * limited_iso;
-        //float wiener_C = 1000.0f;
-        //float wiener_C = 4000.0f;
-
-        // Tapering the wiener scale means that we do more averaging for earlier images in the stack, the
-        // logic being we'll have more chance of ghosting or misalignment with later images.
-        // This helps: testAvg31, testAvg33.
-        // Also slightly helps testAvg17, testAvg23 (slightly less white speckle on tv), testAvg28
-        // (one less white speckle on face).
-        // Note that too much tapering risks increasing ghosting in testAvg26, testAvg39.
-        float tapered_wiener_scale = 1.0f - (float)Math.pow(0.5, avg_factor);
-        if( MyDebug.LOG ) {
-            Log.d(TAG, "avg_factor: " + avg_factor);
-            Log.d(TAG, "tapered_wiener_scale: " + tapered_wiener_scale);
-        }
-        wiener_C /= tapered_wiener_scale;
-
-        float wiener_C_cutoff = wiener_cutoff_factor * wiener_C;
-        if( MyDebug.LOG ) {
-            Log.d(TAG, "wiener_C: " + wiener_C);
-            Log.d(TAG, "wiener_cutoff_factor: " + wiener_cutoff_factor);
-        }
         processAvgScript.set_wiener_C(wiener_C);
         processAvgScript.set_wiener_C_cutoff(wiener_C_cutoff);
 
@@ -1716,7 +1734,7 @@ public class HDRProcessor {
         }
 
         if( hdr_alpha != 0.0f ) {
-            adjustHistogram(allocation0, allocation0, width, height, hdr_alpha, n_tiles, ce_preserve_blacks, time_s);
+            adjustHistogramRS(allocation0, allocation0, width, height, hdr_alpha, n_tiles, ce_preserve_blacks, time_s);
             if( MyDebug.LOG )
                 Log.d(TAG, "### time after adjustHistogram: " + (System.currentTimeMillis() - time_s));
         }
@@ -1758,7 +1776,7 @@ public class HDRProcessor {
 
     /**
      *
-     * @param bitmaps       Only required if use_mtb is true, otherwise may be null.
+     * @param bitmaps       Bitmaps to align.
      * @param base_bitmap   Index of bitmap in bitmaps that should be kept fixed; the other bitmaps
      *                      will be aligned relative to this.
      * @param assume_sorted If assume_sorted if false, and use_mtb is true, this function will also
@@ -1784,16 +1802,23 @@ public class HDRProcessor {
             }
         }
 
+        int n_images = bitmaps.size();
+        if( bitmaps.size() != allocations.length ) {
+            throw new RuntimeException("unequal bitmaps and allocations lengths");
+        }
+        else if( bitmaps.size() != offsets_x.length ) {
+            throw new RuntimeException("unequal bitmaps and offsets_x lengths");
+        }
+        else if( bitmaps.size() != offsets_y.length ) {
+            throw new RuntimeException("unequal bitmaps and offsets_y lengths");
+        }
+
         // initialise
-        for(int i=0;i<offsets_x.length;i++) {
+        for(int i=0;i<n_images;i++) {
             offsets_x[i] = 0;
             offsets_y[i] = 0;
         }
 
-        Allocation [] mtb_allocations = new Allocation[allocations.length];
-        if( MyDebug.LOG )
-            Log.d(TAG, "### time after creating mtb_allocations: " + (System.currentTimeMillis() - time_s));
-
         // Testing shows that in practice we get good results by only aligning the centre quarter of the images. This gives better
         // performance, and uses less memory.
         // If copy_to_centre is false, this has already been done by the caller.
@@ -1811,23 +1836,13 @@ public class HDRProcessor {
             Log.d(TAG, "mtb_x: " + mtb_x);
             Log.d(TAG, "mtb_y: " + mtb_y);
             Log.d(TAG, "mtb_width: " + mtb_width);
-            Log.d(TAG, "mtb_height: " + mtb_height);
-        }
-
-        // create RenderScript
-        if( createMTBScript == null ) {
-            createMTBScript = new ScriptC_create_mtb(rs);
-            if( MyDebug.LOG )
-                Log.d(TAG, "### time after creating createMTBScript: " + (System.currentTimeMillis() - time_s));
+            Log.d(TAG, "mtb_height: " + mtb_height);
         }
-        //ScriptC_create_mtb createMTBScript = new ScriptC_create_mtb(rs);
-        if( MyDebug.LOG )
-            Log.d(TAG, "### time after creating createMTBScript: " + (System.currentTimeMillis() - time_s));
 
         LuminanceInfo [] luminanceInfos = null;
         if( use_mtb ) {
-            luminanceInfos = new LuminanceInfo[allocations.length];
-            for(int i = 0; i < allocations.length; i++) {
+            luminanceInfos = new LuminanceInfo[n_images];
+            for(int i = 0; i < n_images; i++) {
                 luminanceInfos[i] = computeMedianLuminance(bitmaps.get(i), mtb_x, mtb_y, mtb_width, mtb_height);
                 if( MyDebug.LOG )
                     Log.d(TAG, i + ": median_value: " + luminanceInfos[i].median_value);
@@ -1861,7 +1876,7 @@ public class HDRProcessor {
             }
             if( MyDebug.LOG ) {
                 Log.d(TAG, "before sorting:");
-                for(int i=0;i<allocations.length;i++) {
+                for(int i=0;i<n_images;i++) {
                     Log.d(TAG, "    " + i + ": " + luminanceInfos[i]);
                 }
             }
@@ -1881,7 +1896,7 @@ public class HDRProcessor {
             }
             if( MyDebug.LOG ) {
                 Log.d(TAG, "after sorting:");
-                for(int i=0;i<allocations.length;i++) {
+                for(int i=0;i<n_images;i++) {
                     Log.d(TAG, "    " + i + ": " + luminanceInfos[i]);
                 }
             }
@@ -1911,7 +1926,21 @@ public class HDRProcessor {
                 Log.d(TAG, "median_brightness: " + median_brightness);
         }
 
-        for(int i=0;i<allocations.length;i++) {
+        Allocation [] mtb_allocations = new Allocation[n_images];
+        if( MyDebug.LOG )
+            Log.d(TAG, "### time after creating mtb_allocations: " + (System.currentTimeMillis() - time_s));
+
+        // create RenderScript
+        if( createMTBScript == null ) {
+            createMTBScript = new ScriptC_create_mtb(rs);
+            if( MyDebug.LOG )
+                Log.d(TAG, "### time after creating createMTBScript: " + (System.currentTimeMillis() - time_s));
+        }
+        //ScriptC_create_mtb createMTBScript = new ScriptC_create_mtb(rs);
+        if( MyDebug.LOG )
+            Log.d(TAG, "### time after creating createMTBScript: " + (System.currentTimeMillis() - time_s));
+
+        for(int i=0;i<n_images;i++) {
             int median_value = -1;
             if( use_mtb ) {
                 median_value = luminanceInfos[i].median_value;
@@ -1935,8 +1964,6 @@ public class HDRProcessor {
                 continue;
             }
 
-            mtb_allocations[i] = Allocation.createTyped(rs, Type.createXY(rs, Element.U8(rs), mtb_width, mtb_height));
-
             // avoid too low/high median_values, otherwise we'll detect dark or light pixels as "noisy" - needed for testHDR61
             final int min_diff_c = 4; // should be same value as in create_mtb.rs/create_mtb()
             /*if( median_value < min_diff_c+1 || median_value > 255-(min_diff_c+1) ) {
@@ -1947,6 +1974,8 @@ public class HDRProcessor {
             if( MyDebug.LOG )
                 Log.d(TAG, i + ": median_value is now: " + median_value);
 
+            mtb_allocations[i] = Allocation.createTyped(rs, Type.createXY(rs, Element.U8(rs), mtb_width, mtb_height));
+
             // set parameters
             if( use_mtb )
                 createMTBScript.set_median_value(median_value);
@@ -2046,7 +2075,7 @@ public class HDRProcessor {
         alignMTBScript.set_bitmap0(mtb_allocations[base_bitmap]);
         // bitmap1 set below
 
-        for(int i=0;i<allocations.length;i++)  {
+        for(int i=0;i<n_images;i++)  {
             if( i == base_bitmap ) {
                 // don't need to align the "base" reference image
                 continue;
@@ -2077,6 +2106,24 @@ public class HDRProcessor {
 
                 final boolean use_pyramid = false;
                 //final boolean use_pyramid = true;
+
+                int stop_x, stop_y;
+                if( use_pyramid ) {
+                    stop_x = mtb_width;
+                    stop_y = mtb_height;
+                }
+                else {
+                    // see note inside align_mtb.rs/align_mtb() for why we sample over a subset of the image
+                    stop_x = mtb_width/pixel_step_size;
+                    stop_y = mtb_height/pixel_step_size;
+                }
+                if( MyDebug.LOG ) {
+                    Log.d(TAG, "stop_x: " + stop_x);
+                    Log.d(TAG, "stop_y: " + stop_y);
+                }
+
+                int [] errors = new int[9];
+
                 /*if( use_pyramid ) {
                     // downscale by step_size
                     Allocation [] scaled_allocations = new Allocation[2];
@@ -2118,19 +2165,11 @@ public class HDRProcessor {
                 alignMTBScript.invoke_init_errors();
 
                 Script.LaunchOptions launch_options = new Script.LaunchOptions();
-                if( !use_pyramid ) {
-                    // see note inside align_mtb.rs/align_mtb() for why we sample over a subset of the image
-                    int stop_x = mtb_width/pixel_step_size;
-                    int stop_y = mtb_height/pixel_step_size;
-                    if( MyDebug.LOG ) {
-                        Log.d(TAG, "stop_x: " + stop_x);
-                        Log.d(TAG, "stop_y: " + stop_y);
-                    }
-                    //launch_options.setX((int)(stop_x*0.25), (int)(stop_x*0.75));
-                    //launch_options.setY((int)(stop_y*0.25), (int)(stop_y*0.75));
-                    launch_options.setX(0, stop_x);
-                    launch_options.setY(0, stop_y);
-                }
+                //launch_options.setX((int)(stop_x*0.25), (int)(stop_x*0.75));
+                //launch_options.setY((int)(stop_y*0.25), (int)(stop_y*0.75));
+                launch_options.setX(0, stop_x);
+                launch_options.setY(0, stop_y);
+
                 long this_time_s = System.currentTimeMillis();
                 if( use_mtb )
                     alignMTBScript.forEach_align_mtb(mtb_allocations[base_bitmap], launch_options);
@@ -2138,14 +2177,13 @@ public class HDRProcessor {
                     alignMTBScript.forEach_align(mtb_allocations[base_bitmap], launch_options);
                 if( MyDebug.LOG ) {
                     Log.d(TAG, "time for alignMTBScript: " + (System.currentTimeMillis() - this_time_s));
-                    Log.d(TAG, "time after alignMTBScript: " + (System.currentTimeMillis() - time_s));
+                    Log.d(TAG, "### time after alignMTBScript: " + (System.currentTimeMillis() - time_s));
                 }
+                errorsAllocation.copyTo(errors);
+                errorsAllocation.destroy();
 
                 int best_error = -1;
                 int best_id = -1;
-                int [] errors = new int[9];
-                errorsAllocation.copyTo(errors);
-                errorsAllocation.destroy();
                 for(int j=0;j<9;j++) {
                     int this_error = errors[j];
                     if( MyDebug.LOG )
@@ -2215,7 +2253,7 @@ public class HDRProcessor {
             }
         }
 
-        /*for(int i=0;i<allocations.length;i++) {
+        /*for(int i=0;i<n_images;i++) {
             offsets_x[i] = 0;
             offsets_y[i] = 0;
         }*/
@@ -2367,78 +2405,130 @@ public class HDRProcessor {
         return new LuminanceInfo(min_value, 127, hi_value, true);
     }
 
-    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
-    void adjustHistogram(Allocation allocation_in, Allocation allocation_out, int width, int height, float hdr_alpha, int n_tiles, boolean ce_preserve_blacks, long time_s) {
-        if( MyDebug.LOG )
-            Log.d(TAG, "adjustHistogram");
-        final boolean adjust_histogram = false;
-        //final boolean adjust_histogram = true;
-
-        if( adjust_histogram ) {
-            // create histogram
-            int [] histogram = new int[256];
-            if( MyDebug.LOG )
-                Log.d(TAG, "time before creating histogram: " + (System.currentTimeMillis() - time_s));
-            Allocation histogramAllocation = computeHistogramAllocation(allocation_in, false, false, time_s);
-            if( MyDebug.LOG )
-                Log.d(TAG, "time after creating histogram: " + (System.currentTimeMillis() - time_s));
-            histogramAllocation.copyTo(histogram);
-
-                /*if( MyDebug.LOG ) {
-                    // compare/adjust
-                    allocations[0].copyTo(bm);
-                    int [] debug_histogram = new int[256];
-                    for(int i=0;i<256;i++) {
-                        debug_histogram[i] = 0;
-                    }
-                    int [] debug_buffer = new int[width];
-                    for(int y=0;y<height;y++) {
-                        bm.getPixels(debug_buffer, 0, width, 0, y, width, 1);
-                        for(int x=0;x<width;x++) {
-                            int color = debug_buffer[x];
-                            float r = (float)((color & 0xFF0000) >> 16);
-                            float g = (float)((color & 0xFF00) >> 8);
-                            float b = (float)(color & 0xFF);
-                            //float value = 0.299f*r + 0.587f*g + 0.114f*b; // matches ScriptIntrinsicHistogram default behaviour
-                            float value = Math.max(r, g);
-                            value = Math.max(value, b);
-                            int i_value = (int)value;
-                            i_value = Math.min(255, i_value); // just in case
-                            debug_histogram[i_value]++;
-                        }
-                    }
-                    for(int x=0;x<256;x++) {
-                        Log.d(TAG, "histogram[" + x + "] = " + histogram[x] + " debug_histogram: " + debug_histogram[x]);
-                        //histogram[x] = debug_histogram[x];
+    /** Clips the histogram, for Contrast Limited AHE algorithm.
+     * @param histogram Histogram to modify (length 256).
+     * @param temp_c_histogram Temporary workspace (length 256).
+     * @param sub_width Width of the region being processed.
+     * @param sub_height Height of the region being processed.
+     */
+    void clipHistogram(int [] histogram, int [] temp_c_histogram, int sub_width, int sub_height, boolean ce_preserve_blacks) {
+        int n_pixels = sub_width * sub_height;
+        int clip_limit = (5 * n_pixels) / 256;
+                    /*if( MyDebug.LOG ) {
+                        Log.d(TAG, "clip_limit: " + clip_limit);
+                        Log.d(TAG, "    relative clip limit: " + clip_limit*256.0f/n_pixels);
+                    }*/
+        {
+            // find real clip limit
+            int bottom = 0, top = clip_limit;
+            while( top - bottom > 1 ) {
+                int middle = (top + bottom)/2;
+                int sum = 0;
+                for(int x=0;x<256;x++) {
+                    if( histogram[x] > middle ) {
+                        sum += (histogram[x] - clip_limit);
                     }
-                }*/
+                }
+                if( sum > (clip_limit - middle) * 256 )
+                    top = middle;
+                else
+                    bottom = middle;
+            }
+            clip_limit = (top + bottom)/2;
+                        /*if( MyDebug.LOG ) {
+                            Log.d(TAG, "updated clip_limit: " + clip_limit);
+                            Log.d(TAG, "    relative updated clip limit: " + clip_limit*256.0f/n_pixels);
+                        }*/
+        }
+        int n_clipped = 0;
+        for(int x=0;x<256;x++) {
+            if( histogram[x] > clip_limit ) {
+                            /*if( MyDebug.LOG ) {
+                                Log.d(TAG, "    " + x + " : " + histogram[x] + " : " + (histogram[x]*256.0f/n_pixels));
+                            }*/
+                n_clipped += (histogram[x] - clip_limit);
+                histogram[x] = clip_limit;
+            }
+        }
+        int n_clipped_per_bucket = n_clipped / 256;
+                        /*if( MyDebug.LOG ) {
+                            Log.d(TAG, "n_clipped: " + n_clipped);
+                            Log.d(TAG, "n_clipped_per_bucket: " + n_clipped_per_bucket);
+                        }*/
+        for(int x=0;x<256;x++) {
+            histogram[x] += n_clipped_per_bucket;
+        }
+
+        if( ce_preserve_blacks ) {
+            // This helps tests such as testHDR52, testHDR57, testAvg26, testAvg30
+            // The basic idea is that we want to avoid making darker pixels darker (by too
+            // much). We do this by adjusting the histogram:
+            // * We can set a minimum value of each histogram value. E.g., if we set all
+            //   pixels up to a certain brightness to a value equal to n_pixels/256, then
+            //   we prevent those pixels from being made darker. In practice, we choose
+            //   a tapered minimum, starting at (n_pixels/256) for black pixels, linearly
+            //   interpolating to no minimum at brightness 128 (dark_threshold_c).
+            // * For any adjusted value of the histogram, we redistribute, by reducing
+            //   the histogram values of brighter pixels with values larger than (n_pixels/256),
+            //   reducing them to a minimum of (n_pixels/256).
+            // * Lastly, we only modify a given histogram value if pixels of that brightness
+            //   would be made darker by the CLAHE algorithm. We can do this by looking at
+            //   the cumulative histogram (as computed before modifying any values).
+                        /*if( MyDebug.LOG ) {
+                            for(int x=0;x<256;x++) {
+                                Log.d(TAG, "pre-brighten histogram[" + x + "] = " + histogram[x]);
+                            }
+                        }*/
 
-            int [] c_histogram = new int[256];
-            c_histogram[0] = histogram[0];
+            temp_c_histogram[0] = histogram[0];
             for(int x=1;x<256;x++) {
-                c_histogram[x] = c_histogram[x-1] + histogram[x];
+                temp_c_histogram[x] = temp_c_histogram[x-1] + histogram[x];
             }
-                /*if( MyDebug.LOG ) {
-                    for(int x=0;x<256;x++) {
-                        Log.d(TAG, "histogram[" + x + "] = " + histogram[x] + " cumulative: " + c_histogram[x]);
-                    }
-                }*/
-            histogramAllocation.copyFrom(c_histogram);
-
-            /*if( histogramAdjustScript == null ) {
-                histogramAdjustScript = new ScriptC_histogram_adjust(rs);
-            }*/
-            ScriptC_histogram_adjust histogramAdjustScript = new ScriptC_histogram_adjust(rs);
-            histogramAdjustScript.set_c_histogram(histogramAllocation);
-            histogramAdjustScript.set_hdr_alpha(hdr_alpha);
 
+            // avoid making pixels too dark
+            int equal_limit = n_pixels / 256;
             if( MyDebug.LOG )
-                Log.d(TAG, "call histogramAdjustScript");
-            histogramAdjustScript.forEach_histogram_adjust(allocation_in, allocation_out);
-            if( MyDebug.LOG )
-                Log.d(TAG, "time after histogramAdjustScript: " + (System.currentTimeMillis() - time_s));
-            histogramAllocation.destroy();
+                Log.d(TAG, "equal_limit: " + equal_limit);
+            //final int dark_threshold_c = 64;
+            final int dark_threshold_c = 128;
+            //final int dark_threshold_c = 256;
+            for(int x=0;x<dark_threshold_c;x++) {
+                int c_equal_limit = equal_limit * (x+1);
+                if( temp_c_histogram[x] >= c_equal_limit ) {
+                    continue;
+                }
+                float alpha = 1.0f - ((float)x)/((float)dark_threshold_c);
+                //float alpha = 1.0f - ((float)x)/256.0f;
+                int limit = (int)(alpha * equal_limit);
+                //int limit = equal_limit;
+                if( MyDebug.LOG )
+                    Log.d(TAG, "x: " + x + " ; limit: " + limit);
+                            /*histogram[x] = Math.max(histogram[x], limit);
+                            if( MyDebug.LOG )
+                                Log.d(TAG, "    histogram pulled up to: "  + histogram[x]);*/
+                if( histogram[x] < limit ) {
+                    // top up by redistributing later values
+                    for(int y=x+1;y<256 && histogram[x] < limit;y++) {
+                        if( histogram[y] > equal_limit ) {
+                            int move = histogram[y] - equal_limit;
+                            move = Math.min(move, limit - histogram[x]);
+                            histogram[x] += move;
+                            histogram[y] -= move;
+                        }
+                    }
+                    /*if( MyDebug.LOG )
+                        Log.d(TAG, "    histogram pulled up to: "  + histogram[x]);*/
+                                /*if( temp_c_histogram[x] >= c_equal_limit )
+                                    throw new RuntimeException(); // test*/
+                }
+            }
         }
+    }
+
+    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
+    void adjustHistogramRS(Allocation allocation_in, Allocation allocation_out, int width, int height, float hdr_alpha, int n_tiles, boolean ce_preserve_blacks, long time_s) {
+        if( MyDebug.LOG )
+            Log.d(TAG, "adjustHistogram [renderscript]");
 
         //final boolean adjust_histogram_local = false;
         final boolean adjust_histogram_local = true;
@@ -2451,6 +2541,8 @@ public class HDRProcessor {
             // Pizer, Amburn, Austin, Cromartie, Geselowitz, Greer, ter Haar Romeny, Zimmerman, Zuiderveld (1987).
             // Also note that if ce_preserve_blacks is true, we apply a modification to this algorithm, see below.
 
+            if( MyDebug.LOG )
+                Log.d(TAG, "time before creating histograms: " + (System.currentTimeMillis() - time_s));
             // create histograms
             Allocation histogramAllocation = Allocation.createSized(rs, Element.I32(rs), 256);
             /*if( histogramScript == null ) {
@@ -2529,118 +2621,7 @@ public class HDRProcessor {
                             }
                         }*/
 
-                    // clip histogram, for Contrast Limited AHE algorithm
-                    int n_pixels = (stop_x - start_x) * (stop_y - start_y);
-                    int clip_limit = (5 * n_pixels) / 256;
-                    /*if( MyDebug.LOG ) {
-                        Log.d(TAG, "clip_limit: " + clip_limit);
-                        Log.d(TAG, "    relative clip limit: " + clip_limit*256.0f/n_pixels);
-                    }*/
-                    {
-                        // find real clip limit
-                        int bottom = 0, top = clip_limit;
-                        while( top - bottom > 1 ) {
-                            int middle = (top + bottom)/2;
-                            int sum = 0;
-                            for(int x=0;x<256;x++) {
-                                if( histogram[x] > middle ) {
-                                    sum += (histogram[x] - clip_limit);
-                                }
-                            }
-                            if( sum > (clip_limit - middle) * 256 )
-                                top = middle;
-                            else
-                                bottom = middle;
-                        }
-                        clip_limit = (top + bottom)/2;
-                        /*if( MyDebug.LOG ) {
-                            Log.d(TAG, "updated clip_limit: " + clip_limit);
-                            Log.d(TAG, "    relative updated clip limit: " + clip_limit*256.0f/n_pixels);
-                        }*/
-                    }
-                    int n_clipped = 0;
-                    for(int x=0;x<256;x++) {
-                        if( histogram[x] > clip_limit ) {
-                            /*if( MyDebug.LOG ) {
-                                Log.d(TAG, "    " + x + " : " + histogram[x] + " : " + (histogram[x]*256.0f/n_pixels));
-                            }*/
-                            n_clipped += (histogram[x] - clip_limit);
-                            histogram[x] = clip_limit;
-                        }
-                    }
-                    int n_clipped_per_bucket = n_clipped / 256;
-                        /*if( MyDebug.LOG ) {
-                            Log.d(TAG, "n_clipped: " + n_clipped);
-                            Log.d(TAG, "n_clipped_per_bucket: " + n_clipped_per_bucket);
-                        }*/
-                    for(int x=0;x<256;x++) {
-                        histogram[x] += n_clipped_per_bucket;
-                    }
-
-                    if( ce_preserve_blacks ) {
-                        // This helps tests such as testHDR52, testHDR57, testAvg26, testAvg30
-                        // The basic idea is that we want to avoid making darker pixels darker (by too
-                        // much). We do this by adjusting the histogram:
-                        // * We can set a minimum value of each histogram value. E.g., if we set all
-                        //   pixels up to a certain brightness to a value equal to n_pixels/256, then
-                        //   we prevent those pixels from being made darker. In practice, we choose
-                        //   a tapered minimum, starting at (n_pixels/256) for black pixels, linearly
-                        //   interpolating to no minimum at brightness 128 (dark_threshold_c).
-                        // * For any adjusted value of the histogram, we redistribute, by reducing
-                        //   the histogram values of brighter pixels with values larger than (n_pixels/256),
-                        //   reducing them to a minimum of (n_pixels/256).
-                        // * Lastly, we only modify a given histogram value if pixels of that brightness
-                        //   would be made darker by the CLAHE algorithm. We can do this by looking at
-                        //   the cumulative histogram (as computed before modifying any values).
-                        /*if( MyDebug.LOG ) {
-                            for(int x=0;x<256;x++) {
-                                Log.d(TAG, "pre-brighten histogram[" + x + "] = " + histogram[x]);
-                            }
-                        }*/
-
-                        temp_c_histogram[0] = histogram[0];
-                        for(int x=1;x<256;x++) {
-                            temp_c_histogram[x] = temp_c_histogram[x-1] + histogram[x];
-                        }
-
-                        // avoid making pixels too dark
-                        int equal_limit = n_pixels / 256;
-                        if( MyDebug.LOG )
-                            Log.d(TAG, "equal_limit: " + equal_limit);
-                        //final int dark_threshold_c = 64;
-                        final int dark_threshold_c = 128;
-                        //final int dark_threshold_c = 256;
-                        for(int x=0;x<dark_threshold_c;x++) {
-                            int c_equal_limit = equal_limit * (x+1);
-                            if( temp_c_histogram[x] >= c_equal_limit ) {
-                                continue;
-                            }
-                            float alpha = 1.0f - ((float)x)/((float)dark_threshold_c);
-                            //float alpha = 1.0f - ((float)x)/256.0f;
-                            int limit = (int)(alpha * equal_limit);
-                            //int limit = equal_limit;
-                            if( MyDebug.LOG )
-                                Log.d(TAG, "x: " + x + " ; limit: " + limit);
-                            /*histogram[x] = Math.max(histogram[x], limit);
-                            if( MyDebug.LOG )
-                                Log.d(TAG, "    histogram pulled up to: "  + histogram[x]);*/
-                            if( histogram[x] < limit ) {
-                                // top up by redistributing later values
-                                for(int y=x+1;y<256 && histogram[x] < limit;y++) {
-                                    if( histogram[y] > equal_limit ) {
-                                        int move = histogram[y] - equal_limit;
-                                        move = Math.min(move, limit - histogram[x]);
-                                        histogram[x] += move;
-                                        histogram[y] -= move;
-                                    }
-                                }
-                                if( MyDebug.LOG )
-                                    Log.d(TAG, "    histogram pulled up to: "  + histogram[x]);
-                                /*if( temp_c_histogram[x] >= c_equal_limit )
-                                    throw new RuntimeException(); // test*/
-                            }
-                        }
-                    }
+                    clipHistogram(histogram, temp_c_histogram, (stop_x - start_x), (stop_y - start_y), ce_preserve_blacks);
 
                     // compute cumulative histogram
                     int histogram_offset = 256*(i*n_tiles+j);
@@ -2648,16 +2629,16 @@ public class HDRProcessor {
                     for(int x=1;x<256;x++) {
                         c_histogram[histogram_offset+x] = c_histogram[histogram_offset+x-1] + histogram[x];
                     }
-                    if( MyDebug.LOG ) {
+                    /*if( MyDebug.LOG ) {
                         for(int x=0;x<256;x++) {
                             Log.d(TAG, "histogram[" + x + "] = " + histogram[x] + " cumulative: " + c_histogram[histogram_offset+x]);
                         }
-                    }
+                    }*/
                 }
             }
 
             if( MyDebug.LOG )
-                Log.d(TAG, "time after creating histograms: " + (System.currentTimeMillis() - time_s));
+                Log.d(TAG, "adjustHistogram: time after creating histograms: " + (System.currentTimeMillis() - time_s));
 
             Allocation c_histogramAllocation = Allocation.createSized(rs, Element.I32(rs), n_tiles*n_tiles*256);
             c_histogramAllocation.copyFrom(c_histogram);
@@ -2682,7 +2663,7 @@ public class HDRProcessor {
         }
     }
 
-    /**
+    /** Only call this from computeHistogram()!
      * @param avg If true, compute the color value as the average of the rgb values. If false,
      *            compute the color value as the maximum of the rgb values.
      * @param floating_point Whether the allocation_in is in floating point (F32_3) format, or
@@ -2745,28 +2726,41 @@ public class HDRProcessor {
      */
     @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
     public int [] computeHistogram(Bitmap bitmap, boolean avg) {
-        if( MyDebug.LOG )
-            Log.d(TAG, "computeHistogram");
+        if( MyDebug.LOG ) {
+            Log.d(TAG, "computeHistogram [bitmap]");
+            Log.d(TAG, "avg: " + avg);
+        }
         long time_s = System.currentTimeMillis();
         initRenderscript();
         Allocation allocation_in = Allocation.createFromBitmap(rs, bitmap);
         if( MyDebug.LOG )
             Log.d(TAG, "time after createFromBitmap: " + (System.currentTimeMillis() - time_s));
-        int [] histogram = computeHistogram(allocation_in, avg, false);
+        int [] histogram = computeHistogram(allocation_in, bitmap.getWidth(), bitmap.getHeight(), avg, false);
         allocation_in.destroy();
         freeScripts();
+        if( MyDebug.LOG ) {
+            Log.d(TAG, "image size: " + bitmap.getWidth() + " x " + bitmap.getHeight());
+            Log.d(TAG, "### time to compute histogram: " + (System.currentTimeMillis() - time_s));
+        }
         return histogram;
     }
 
     @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
-    private int [] computeHistogram(Allocation allocation, boolean avg, boolean floating_point) {
-        if( MyDebug.LOG )
-            Log.d(TAG, "computeHistogram");
+    private int [] computeHistogram(Allocation allocation, int width, int height, boolean avg, boolean floating_point) {
+        if( MyDebug.LOG ) {
+            Log.d(TAG, "computeHistogram [allocation]");
+            Log.d(TAG, "avg: " + avg);
+            Log.d(TAG, "floating_point: " + floating_point);
+        }
         long time_s = System.currentTimeMillis();
         int [] histogram = new int[256];
         Allocation histogramAllocation = computeHistogramAllocation(allocation, avg, floating_point, time_s);
         histogramAllocation.copyTo(histogram);
         histogramAllocation.destroy();
+        if( MyDebug.LOG ) {
+            Log.d(TAG, "allocation size: " + width + " x " + height);
+            Log.d(TAG, "### time to compute histogram: " + (System.currentTimeMillis() - time_s));
+        }
         return histogram;
     }
 
@@ -2980,8 +2974,35 @@ public class HDRProcessor {
         return new BrightenFactors(gain, low_x, mid_x, gamma);
     }
 
+    private float computeBlackLevel(HistogramInfo histogramInfo, int [] histo, int iso) {
+        float black_level = 0.0f;
+        {
+            // quick and dirty dehaze algorithm
+            // helps (among others): testAvg1 to testAvg10, testAvg27, testAvg30, testAvg31, testAvg39, testAvg40
+            int total = histogramInfo.total;
+            int percentile = (int)(total*0.001f);
+            int count = 0;
+            int darkest_brightness = -1;
+            for(int i = 0; i < histo.length; i++) {
+                count += histo[i];
+                if( count >= percentile && darkest_brightness == -1 ) {
+                    darkest_brightness = i;
+                }
+            }
+            black_level = Math.max(black_level, darkest_brightness);
+            // don't allow black_level too high for "dark" images, as this can cause problems due to exaggerating noise (e.g.,
+            // see testAvg38)
+            black_level = Math.min(black_level, iso <= 700 ? 18 : 4);
+            if( MyDebug.LOG ) {
+                Log.d(TAG, "percentile: " + percentile);
+                Log.d(TAG, "darkest_brightness: " + darkest_brightness);
+                Log.d(TAG, "black_level is now: " + black_level);
+            }
+        }
+        return black_level;
+    }
+
     /** Final stage of the noise reduction algorithm.
-     *  Note that the returned bitmap will be scaled up by the factor returned by getAvgSampleSize().
      * @param input         The allocation in floating point format.
      * @param width         Width of the input.
      * @param height        Height of the input.
@@ -2990,9 +3011,9 @@ public class HDRProcessor {
      * @return              Resultant bitmap.
      */
     @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
-    public Bitmap avgBrighten(Allocation input, int width, int height, int iso, long exposure_time) {
+    private Bitmap avgBrightenRS(Allocation input, int width, int height, int iso, long exposure_time) {
         if( MyDebug.LOG ) {
-            Log.d(TAG, "avgBrighten");
+            Log.d(TAG, "avgBrightenRS");
             Log.d(TAG, "iso: " + iso);
             Log.d(TAG, "exposure_time: " + exposure_time);
         }
@@ -3000,7 +3021,7 @@ public class HDRProcessor {
 
         long time_s = System.currentTimeMillis();
 
-        int [] histo = computeHistogram(input, false, true);
+        int [] histo = computeHistogram(input, width, height, false, true);
         HistogramInfo histogramInfo = getHistogramInfo(histo);
         int brightness = histogramInfo.median_brightness;
         int max_brightness = histogramInfo.max_brightness;
@@ -3011,6 +3032,9 @@ public class HDRProcessor {
             Log.d(TAG, "median brightness: " + histogramInfo.median_brightness);
             Log.d(TAG, "mean brightness: " + histogramInfo.mean_brightness);
             Log.d(TAG, "max brightness: " + max_brightness);
+            /*for(int i=0;i<256;i++) {
+                Log.d(TAG, "histogram[" + i + "]: " + histo[i]);
+            }*/
         }
 
         BrightenFactors brighten_factors = computeBrightenFactors(true, iso, exposure_time, brightness, max_brightness);
@@ -3038,88 +3062,25 @@ public class HDRProcessor {
             }
         }*/
 
+        float black_level = computeBlackLevel(histogramInfo, histo, iso);
+
+        // use a lower medial filter strength for pixel binned images, so that we don't blur testAvg46 so much (especially sign text)
+        float median_filter_strength = (cached_avg_sample_size >= 2) ? 0.5f : 1.0f;
+        if( MyDebug.LOG )
+            Log.d(TAG, "median_filter_strength: " + median_filter_strength);
+
         /*if( avgBrightenScript == null ) {
             avgBrightenScript = new ScriptC_avg_brighten(rs);
         }*/
         ScriptC_avg_brighten avgBrightenScript = new ScriptC_avg_brighten(rs);
         avgBrightenScript.set_bitmap(input);
-        float black_level = 0.0f;
-        {
-            // quick and dirty dehaze algorithm
-            // helps (among others): testAvg1 to testAvg10, testAvg27, testAvg30, testAvg31, testAvg39, testAvg40
-            int total = histogramInfo.total;
-            int percentile = (int)(total*0.001f);
-            int count = 0;
-            int darkest_brightness = -1;
-            for(int i = 0; i < histo.length; i++) {
-                count += histo[i];
-                if( count >= percentile && darkest_brightness == -1 ) {
-                    darkest_brightness = i;
-                }
-            }
-            black_level = Math.max(black_level, darkest_brightness);
-            // don't allow black_level too high for "dark" images, as this can cause problems due to exaggerating noise (e.g.,
-            // see testAvg38)
-            black_level = Math.min(black_level, iso <= 700 ? 18 : 4);
-            if( MyDebug.LOG ) {
-                Log.d(TAG, "percentile: " + percentile);
-                Log.d(TAG, "darkest_brightness: " + darkest_brightness);
-                Log.d(TAG, "black_level is now: " + black_level);
-            }
-        }
         avgBrightenScript.invoke_setBlackLevel(black_level);
 
-        // use a lower medial filter strength for pixel binned images, so that we don't blur testAvg46 so much (especially sign text)
-        float median_filter_strength = (cached_avg_sample_size >= 2) ? 0.5f : 1.0f;
-        if( MyDebug.LOG )
-            Log.d(TAG, "median_filter_strength: " + median_filter_strength);
         avgBrightenScript.set_median_filter_strength(median_filter_strength);
         avgBrightenScript.invoke_setBrightenParameters(gain, gamma, low_x, mid_x, max_brightness);
 
-        /*float tonemap_scale_c = 255.0f;
-        if( MyDebug.LOG )
-            Log.d(TAG, "tonemap_scale_c: " + tonemap_scale_c);
-        avgBrightenScript.set_tonemap_scale(tonemap_scale_c);
-
-        float max_possible_value = gain*max_brightness;
-        if( MyDebug.LOG )
-            Log.d(TAG, "max_possible_value: " + max_possible_value);
-        if( max_possible_value < 255.0f ) {
-            max_possible_value = 255.0f; // don't make dark images too bright
-            if( MyDebug.LOG )
-                Log.d(TAG, "clamp max_possible_value to: " + max_possible_value);
-        }
-        float linear_scale = (max_possible_value + tonemap_scale_c) / max_possible_value;
-        if( MyDebug.LOG )
-            Log.d(TAG, "linear_scale: " + linear_scale);
-        avgBrightenScript.set_linear_scale(linear_scale);*/
-
-        /*{
-            max_possible_value = max_brightness;
-            float tonemap_scale_c = 255.0f;
-            if( 255.0f / max_possible_value < ((float)brightness_target)/(float)brightness + brightness_target / 255.0f - 1.0f ) {
-                final float tonemap_denom = ((float)brightness_target)/(float)brightness - (255.0f / max_possible_value);
-                if( MyDebug.LOG )
-                    Log.d(TAG, "tonemap_denom: " + tonemap_denom);
-                if( tonemap_denom != 0.0f ) // just in case
-                    tonemap_scale_c = (255.0f - brightness_target) / tonemap_denom;
-                //throw new RuntimeException(); // test
-            }
-            // Higher tonemap_scale_c values means darker results from the Reinhard tonemapping.
-            // Colours brighter than 255-tonemap_scale_c will be made darker, colours darker than 255-tonemap_scale_c will be made brighter
-            // (tonemap_scale_c==255 means therefore that colours will only be made darker).
-            if( MyDebug.LOG )
-                Log.d(TAG, "tonemap_scale_c: " + tonemap_scale_c);
-            avgBrightenScript.set_tonemap_scale(tonemap_scale_c);
-
-            float linear_scale = (max_possible_value + tonemap_scale_c) / max_possible_value;
-            if( MyDebug.LOG )
-                Log.d(TAG, "linear_scale: " + linear_scale);
-            avgBrightenScript.set_linear_scale(linear_scale);
-        }*/
-
-        Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
-        Allocation allocation_out = Allocation.createFromBitmap(rs, bitmap);
+        Bitmap output_bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
+        Allocation allocation_out = Allocation.createFromBitmap(rs, output_bitmap);
         if( MyDebug.LOG )
             Log.d(TAG, "### time after creating allocation_out: " + (System.currentTimeMillis() - time_s));
 
@@ -3149,31 +3110,33 @@ public class HDRProcessor {
                 Log.d(TAG, "dro alpha: " + alpha);
                 Log.d(TAG, "dro amount: " + amount);
             }
-            adjustHistogram(allocation_out, allocation_out, width, height, amount, 1, true, time_s);
+            adjustHistogramRS(allocation_out, allocation_out, width, height, amount, 1, true, time_s);
             if( MyDebug.LOG )
                 Log.d(TAG, "### time after adjustHistogram: " + (System.currentTimeMillis() - time_s));
         }
 
-        allocation_out.copyTo(bitmap);
+        allocation_out.copyTo(output_bitmap);
         allocation_out.destroy();
         if( MyDebug.LOG )
             Log.d(TAG, "### time after copying to bitmap: " + (System.currentTimeMillis() - time_s));
 
-        /*int sample_size = getAvgSampleSize();
-        if( MyDebug.LOG )
-            Log.d(TAG, "sample_size: " + sample_size);
-        if( sample_size > 1 ) {
-            Matrix matrix = new Matrix();
-            matrix.postScale(sample_size, sample_size);
-            Bitmap new_bitmap = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix, true);
-            bitmap.recycle();
-            bitmap = new_bitmap;
-        }*/
-
         freeScripts();
         if( MyDebug.LOG )
             Log.d(TAG, "### total time for avgBrighten: " + (System.currentTimeMillis() - time_s));
-        return bitmap;
+        return output_bitmap;
+    }
+
+    /** Final stage of the noise reduction algorithm.
+     * @param avg_data       AvgData returned from call to processAvg().
+     * @param width          Width of the input.
+     * @param height         Height of the input.
+     * @param iso            ISO used for the original images.
+     * @param exposure_time  Exposure time used for the original images.
+     * @return               Resultant bitmap.
+     */
+    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
+    public Bitmap avgBrighten(AvgData avg_data, int width, int height, int iso, long exposure_time) {
+        return avgBrightenRS(avg_data.allocation_out, width, height, iso, exposure_time);
     }
 
     /**
diff --git a/app/src/main/java/net/sourceforge/opencamera/ImageSaver.java b/app/src/main/java/net/sourceforge/opencamera/ImageSaver.java
index e808c4697183c186ed378dc473afcc0d8f3e00db..af7d78f0df2b54bf729f3b31c4a4835035cb5fa0 100644
--- a/app/src/main/java/net/sourceforge/opencamera/ImageSaver.java
+++ b/app/src/main/java/net/sourceforge/opencamera/ImageSaver.java
@@ -64,6 +64,10 @@ import foundation.e.camera.R;
 public class ImageSaver extends Thread {
     private static final String TAG = "ImageSaver";
 
+    static final String hdr_suffix = "_HDR";
+    static final String nr_suffix = "_NR";
+    static final String pano_suffix = "_PANO";
+
     private final Paint p = new Paint();
 
     private final MainActivity main_activity;
@@ -77,7 +81,7 @@ public class ImageSaver extends Thread {
      * Also note, main_activity.imageQueueChanged() should be called on UI thread after n_images_to_save increases or
      * decreases.
      * Access to n_images_to_save should always be synchronized to this (i.e., the ImageSaver class).
-     * n_real_images_to_save excludes "Dummy" requests, and should also be synchronized, and modified
+     * n_real_images_to_save excludes "Dummy" or "on_destroy" requests, and should also be synchronized, and modified
      * at the same time as n_images_to_save.
      */
     private int n_images_to_save = 0;
@@ -104,7 +108,8 @@ public class ImageSaver extends Thread {
         enum Type {
             JPEG, // also covers WEBP
             RAW,
-            DUMMY
+            DUMMY,
+            ON_DESTROY // indicate that application is being destroyed, so should exit thread
         }
         final Type type;
         enum ProcessType {
@@ -136,7 +141,7 @@ public class ImageSaver extends Thread {
         final boolean using_camera2;
         final boolean using_camera_extensions;
         /* image_format allows converting the standard JPEG image into another file format.
-#		 */
+#        */
         enum ImageFormat {
             STD, // leave unchanged from the standard JPEG format
             WEBP,
@@ -296,6 +301,7 @@ public class ImageSaver extends Thread {
     }
 
     ImageSaver(MainActivity main_activity) {
+        super("ImageSaver");
         if( MyDebug.LOG )
             Log.d(TAG, "ImageSaver");
         this.main_activity = main_activity;
@@ -486,6 +492,38 @@ public class ImageSaver extends Thread {
     void onDestroy() {
         if( MyDebug.LOG )
             Log.d(TAG, "onDestroy");
+        {
+            //  a request so that the imagesaver thread will complete
+            Request request = new Request(Request.Type.ON_DESTROY,
+                    Request.ProcessType.NORMAL,
+                    false,
+                    0,
+                    Request.SaveBase.SAVEBASE_NONE,
+                    null,
+                    null,
+                    false, null,
+                    false, false,
+                    Request.ImageFormat.STD, 0,
+                    false, 0.0, null,
+                    false,
+                    false,
+                    null,
+                    HDRProcessor.default_tonemapping_algorithm_c,
+                    null,
+                    0,
+                    0,
+                    1.0f,
+                    null, null, 0, 0, null, null, null, null,
+                    //null,
+                    null,
+                    false, Request.RemoveDeviceExif.OFF, false, null, false, 0.0,
+                    0.0, false,
+                    null, null,
+                    1);
+            if( MyDebug.LOG )
+                Log.d(TAG, "add on_destroy request");
+            addRequest(request, 1);
+        }
         if( panoramaProcessor != null ) {
             panoramaProcessor.onDestroy();
         }
@@ -508,6 +546,7 @@ public class ImageSaver extends Thread {
                 if( MyDebug.LOG )
                     Log.d(TAG, "ImageSaver thread found new request from queue, size is now: " + queue.size());
                 boolean success;
+                boolean on_destroy = false;
                 switch (request.type) {
                     case RAW:
                         if (MyDebug.LOG)
@@ -524,6 +563,12 @@ public class ImageSaver extends Thread {
                             Log.d(TAG, "request is dummy");
                         success = true;
                         break;
+                    case ON_DESTROY:
+                        if( MyDebug.LOG )
+                            Log.d(TAG, "request is on_destroy");
+                        success = true;
+                        on_destroy = true;
+                        break;
                     default:
                         if (MyDebug.LOG)
                             Log.e(TAG, "request is unknown type!");
@@ -543,7 +588,7 @@ public class ImageSaver extends Thread {
                 }
                 synchronized( this ) {
                     n_images_to_save--;
-                    if( request.type != Request.Type.DUMMY )
+                    if( request.type != Request.Type.DUMMY && request.type != Request.Type.ON_DESTROY )
                         n_real_images_to_save--;
                     if( MyDebug.LOG )
                         Log.d(TAG, "ImageSaver thread processed new request from queue, images to save is now: " + n_images_to_save);
@@ -563,6 +608,9 @@ public class ImageSaver extends Thread {
                         }
                     });
                 }
+                if( on_destroy ) {
+                    break;
+                }
             }
             catch(InterruptedException e) {
                 e.printStackTrace();
@@ -570,6 +618,8 @@ public class ImageSaver extends Thread {
                     Log.e(TAG, "interrupted while trying to read from ImageSaver queue");
             }
         }
+        if( MyDebug.LOG )
+            Log.d(TAG, "stopping ImageSaver thread...");
     }
 
     /** Saves a photo.
@@ -911,7 +961,7 @@ public class ImageSaver extends Thread {
                     // but we synchronize modification to avoid risk of problems related to compiler optimisation (local caching or reordering)
                     // also see FindBugs warning due to inconsistent synchronisation
                     n_images_to_save++; // increment before adding to the queue, just to make sure the main thread doesn't think we're all done
-                    if( request.type != Request.Type.DUMMY )
+                    if( request.type != Request.Type.DUMMY && request.type != Request.Type.ON_DESTROY )
                         n_real_images_to_save++;
 
                     main_activity.runOnUiThread(new Runnable() {
@@ -1056,6 +1106,7 @@ public class ImageSaver extends Thread {
         final BitmapFactory.Options options;
         final byte [] jpeg;
         LoadBitmapThread(BitmapFactory.Options options, byte [] jpeg) {
+            super("LoadBitmapThread");
             this.options = options;
             this.jpeg = jpeg;
         }
@@ -1370,36 +1421,36 @@ public class ImageSaver extends Thread {
             saveBaseImages(request, "_");
             main_activity.savingImage(true);
 
-			/*List<Bitmap> bitmaps = loadBitmaps(request.jpeg_images, 0);
-			if (bitmaps == null) {
-				if (MyDebug.LOG)
-					Log.e(TAG, "failed to load bitmaps");
-				main_activity.savingImage(false);
-				return false;
-			}*/
-			/*Bitmap nr_bitmap = loadBitmap(request.jpeg_images.get(0), true);
-
-			if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP ) {
-				try {
-					for(int i = 1; i < request.jpeg_images.size(); i++) {
-						Log.d(TAG, "processAvg for image: " + i);
-						Bitmap new_bitmap = loadBitmap(request.jpeg_images.get(i), false);
-						float avg_factor = (float) i;
-						hdrProcessor.processAvg(nr_bitmap, new_bitmap, avg_factor, true);
-						// processAvg recycles new_bitmap
-					}
-					//hdrProcessor.processAvgMulti(bitmaps, hdr_strength, 4);
-					//hdrProcessor.avgBrighten(nr_bitmap);
-				}
-				catch(HDRProcessorException e) {
-					e.printStackTrace();
-					throw new RuntimeException();
-				}
-			}
-			else {
-				Log.e(TAG, "shouldn't have offered NoiseReduction as an option if not on Android 5");
-				throw new RuntimeException();
-			}*/
+            /*List<Bitmap> bitmaps = loadBitmaps(request.jpeg_images, 0);
+            if (bitmaps == null) {
+                if (MyDebug.LOG)
+                    Log.e(TAG, "failed to load bitmaps");
+                main_activity.savingImage(false);
+                return false;
+            }*/
+            /*Bitmap nr_bitmap = loadBitmap(request.jpeg_images.get(0), true);
+
+            if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP ) {
+                try {
+                    for(int i = 1; i < request.jpeg_images.size(); i++) {
+                        Log.d(TAG, "processAvg for image: " + i);
+                        Bitmap new_bitmap = loadBitmap(request.jpeg_images.get(i), false);
+                        float avg_factor = (float) i;
+                        hdrProcessor.processAvg(nr_bitmap, new_bitmap, avg_factor, true);
+                        // processAvg recycles new_bitmap
+                    }
+                    //hdrProcessor.processAvgMulti(bitmaps, hdr_strength, 4);
+                    //hdrProcessor.avgBrighten(nr_bitmap);
+                }
+                catch(HDRProcessorException e) {
+                    e.printStackTrace();
+                    throw new RuntimeException();
+                }
+            }
+            else {
+                Log.e(TAG, "shouldn't have offered NoiseReduction as an option if not on Android 5");
+                throw new RuntimeException();
+            }*/
             Bitmap nr_bitmap;
             if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP ) {
                 try {
@@ -1418,12 +1469,12 @@ public class ImageSaver extends Thread {
                     List<Bitmap> bitmaps = null;
                     Bitmap bitmap0, bitmap1;
                     if( use_smp ) {
-						/*List<byte []> sub_jpeg_list = new ArrayList<>();
-						sub_jpeg_list.add(request.jpeg_images.get(0));
-						sub_jpeg_list.add(request.jpeg_images.get(1));
-						bitmaps = loadBitmaps(sub_jpeg_list, -1, inSampleSize);
-						bitmap0 = bitmaps.get(0);
-						bitmap1 = bitmaps.get(1);*/
+                        /*List<byte []> sub_jpeg_list = new ArrayList<>();
+                        sub_jpeg_list.add(request.jpeg_images.get(0));
+                        sub_jpeg_list.add(request.jpeg_images.get(1));
+                        bitmaps = loadBitmaps(sub_jpeg_list, -1, inSampleSize);
+                        bitmap0 = bitmaps.get(0);
+                        bitmap1 = bitmaps.get(1);*/
                         int n_remaining = request.jpeg_images.size();
                         int n_load = Math.min(n_smp_images, n_remaining);
                         if( MyDebug.LOG ) {
@@ -1459,7 +1510,6 @@ public class ImageSaver extends Thread {
                     if( MyDebug.LOG ) {
                         Log.d(TAG, "*** time for processing first two bitmaps: " + (System.currentTimeMillis() - this_time_s));
                     }
-                    Allocation allocation = avg_data.allocation_out;
 
                     for(int i=2;i<request.jpeg_images.size();i++) {
                         if( MyDebug.LOG )
@@ -1514,7 +1564,7 @@ public class ImageSaver extends Thread {
                     }
 
                     this_time_s = System.currentTimeMillis();
-                    nr_bitmap = hdrProcessor.avgBrighten(allocation, width, height, request.iso, request.exposure_time);
+                    nr_bitmap = hdrProcessor.avgBrighten(avg_data, width, height, request.iso, request.exposure_time);
                     if( MyDebug.LOG ) {
                         Log.d(TAG, "*** time for brighten: " + (System.currentTimeMillis() - this_time_s));
                     }
@@ -1542,8 +1592,7 @@ public class ImageSaver extends Thread {
 
             if( MyDebug.LOG )
                 Log.d(TAG, "save NR image");
-            String suffix = "_NR";
-            success = saveSingleImageNow(request, request.jpeg_images.get(0), nr_bitmap, suffix, true, true, true, false);
+            success = saveSingleImageNow(request, request.jpeg_images.get(0), nr_bitmap, nr_suffix, true, true, true, false);
             if( MyDebug.LOG && !success )
                 Log.e(TAG, "saveSingleImageNow failed for nr image");
             nr_bitmap.recycle();
@@ -1637,7 +1686,7 @@ public class ImageSaver extends Thread {
             int base_image_id = ((request.jpeg_images.size()-1)/2);
             if( MyDebug.LOG )
                 Log.d(TAG, "base_image_id: " + base_image_id);
-            String suffix = request.jpeg_images.size() == 1 ? "_DRO" : "_HDR";
+            String suffix = request.jpeg_images.size() == 1 ? "_DRO" : hdr_suffix;
             success = saveSingleImageNow(request, request.jpeg_images.get(base_image_id), hdr_bitmap, suffix, true, true, true, false);
             if( MyDebug.LOG && !success )
                 Log.e(TAG, "saveSingleImageNow failed for hdr image");
@@ -1653,28 +1702,28 @@ public class ImageSaver extends Thread {
 
             // save text file with gyro info
             if( !request.image_capture_intent && request.save_base == Request.SaveBase.SAVEBASE_ALL_PLUS_DEBUG ) {
-				/*final StringBuilder gyro_text = new StringBuilder();
-				gyro_text.append("Panorama gyro debug info\n");
-				gyro_text.append("n images: " + request.gyro_rotation_matrix.size() + ":\n");
+                /*final StringBuilder gyro_text = new StringBuilder();
+                gyro_text.append("Panorama gyro debug info\n");
+                gyro_text.append("n images: " + request.gyro_rotation_matrix.size() + ":\n");
 
-				float [] inVector = new float[3];
-				float [] outVector = new float[3];
-				for(int i=0;i<request.gyro_rotation_matrix.size();i++) {
-					gyro_text.append("Image " + i + ":\n");
+                float [] inVector = new float[3];
+                float [] outVector = new float[3];
+                for(int i=0;i<request.gyro_rotation_matrix.size();i++) {
+                    gyro_text.append("Image " + i + ":\n");
 
-					GyroSensor.setVector(inVector, 1.0f, 0.0f, 0.0f); // vector pointing in "right" direction
-					GyroSensor.transformVector(outVector, request.gyro_rotation_matrix.get(i), inVector);
-					gyro_text.append("    X: " + outVector[0] + " , " + outVector[1] + " , " + outVector[2] + "\n");
+                    GyroSensor.setVector(inVector, 1.0f, 0.0f, 0.0f); // vector pointing in "right" direction
+                    GyroSensor.transformVector(outVector, request.gyro_rotation_matrix.get(i), inVector);
+                    gyro_text.append("    X: " + outVector[0] + " , " + outVector[1] + " , " + outVector[2] + "\n");
 
-					GyroSensor.setVector(inVector, 0.0f, 1.0f, 0.0f); // vector pointing in "up" direction
-					GyroSensor.transformVector(outVector, request.gyro_rotation_matrix.get(i), inVector);
-					gyro_text.append("    Y: " + outVector[0] + " , " + outVector[1] + " , " + outVector[2] + "\n");
+                    GyroSensor.setVector(inVector, 0.0f, 1.0f, 0.0f); // vector pointing in "up" direction
+                    GyroSensor.transformVector(outVector, request.gyro_rotation_matrix.get(i), inVector);
+                    gyro_text.append("    Y: " + outVector[0] + " , " + outVector[1] + " , " + outVector[2] + "\n");
 
-					GyroSensor.setVector(inVector, 0.0f, 0.0f, -1.0f); // vector pointing behind the device's screen
-					GyroSensor.transformVector(outVector, request.gyro_rotation_matrix.get(i), inVector);
-					gyro_text.append("    -Z: " + outVector[0] + " , " + outVector[1] + " , " + outVector[2] + "\n");
+                    GyroSensor.setVector(inVector, 0.0f, 0.0f, -1.0f); // vector pointing behind the device's screen
+                    GyroSensor.transformVector(outVector, request.gyro_rotation_matrix.get(i), inVector);
+                    gyro_text.append("    -Z: " + outVector[0] + " , " + outVector[1] + " , " + outVector[2] + "\n");
 
-				}*/
+                }*/
 
                 try {
                     StringWriter writer = new StringWriter();
@@ -1683,16 +1732,16 @@ public class ImageSaver extends Thread {
 
                     StorageUtils storageUtils = main_activity.getStorageUtils();
                     /*File saveFile = null;
-					Uri saveUri = null;
-					if( storageUtils.isUsingSAF() ) {
-						saveUri = storageUtils.createOutputMediaFileSAF(StorageUtils.MEDIA_TYPE_GYRO_INFO, "", "xml", request.current_date);
-					}
-					else {
+                    Uri saveUri = null;
+                    if( storageUtils.isUsingSAF() ) {
+                        saveUri = storageUtils.createOutputMediaFileSAF(StorageUtils.MEDIA_TYPE_GYRO_INFO, "", "xml", request.current_date);
+                    }
+                    else {
                         saveFile = storageUtils.createOutputMediaFile(StorageUtils.MEDIA_TYPE_GYRO_INFO, "", "xml", request.current_date);
                         if( MyDebug.LOG )
                             Log.d(TAG, "save to: " + saveFile.getAbsolutePath());
                     }*/
-					// We save to the application specific folder so this works on Android 10 with scoped storage, without having to
+                    // We save to the application specific folder so this works on Android 10 with scoped storage, without having to
                     // rewrite the non-SAF codepath to use MediaStore API (which would also have problems that the gyro debug files would
                     // show up in the MediaStore, hence gallery applications!)
                     // We use this for older Android versions for consistency, plus not a bad idea of to have debug files in the application
@@ -1733,9 +1782,9 @@ public class ImageSaver extends Thread {
             //String suffix = "_";
             //success = saveImages(request, suffix, false, true, true);
 
-			saveBaseImages(request, "_");
+            saveBaseImages(request, "_");
 
-			main_activity.savingImage(true);
+            main_activity.savingImage(true);
 
             long time_s = System.currentTimeMillis();
 
@@ -1802,12 +1851,11 @@ public class ImageSaver extends Thread {
             bitmaps.clear();
             System.gc();
 
-			main_activity.savingImage(false);
+            main_activity.savingImage(false);
 
             if( MyDebug.LOG )
                 Log.d(TAG, "save panorama image");
-            String suffix = "_PANO";
-            success = saveSingleImageNow(request, request.jpeg_images.get(0), panorama, suffix, true, true, true, true);
+            success = saveSingleImageNow(request, request.jpeg_images.get(0), panorama, pano_suffix, true, true, true, true);
             if( MyDebug.LOG && !success )
                 Log.e(TAG, "saveSingleImageNow failed for panorama image");
             panorama.recycle();
@@ -1987,13 +2035,13 @@ public class ImageSaver extends Thread {
                 Log.d(TAG, "decoded bitmap size " + width + ", " + height);
                 Log.d(TAG, "bitmap size: " + width*height*4);
             }
-    			/*for(int y=0;y<height;y++) {
-    				for(int x=0;x<width;x++) {
-    					int col = bitmap.getPixel(x, y);
-    					col = col & 0xffff0000; // mask out red component
-    					bitmap.setPixel(x, y, col);
-    				}
-    			}*/
+                /*for(int y=0;y<height;y++) {
+                    for(int x=0;x<width;x++) {
+                        int col = bitmap.getPixel(x, y);
+                        col = col & 0xffff0000; // mask out red component
+                        bitmap.setPixel(x, y, col);
+                    }
+                }*/
             Matrix matrix = new Matrix();
             double level_angle_rad_abs = Math.abs( Math.toRadians(level_angle) );
             int w1 = width, h1 = height;
@@ -3478,9 +3526,6 @@ public class ImageSaver extends Thread {
         }
 
         modifyExif(exif_new, request.remove_device_exif, request.type == Request.Type.JPEG, request.using_camera2, request.using_camera_extensions, request.current_date, request.store_location, request.location, request.store_geo_direction, request.geo_direction, request.custom_tag_artist, request.custom_tag_copyright, request.level_angle, request.pitch_angle, request.store_ypr);
-        if( request.remove_device_exif == Request.RemoveDeviceExif.OFF || request.remove_device_exif == Request.RemoveDeviceExif.KEEP_DATETIME ) {
-            setDateTimeExif(exif_new);
-        }
 
         removeExifTags(exif_new, request); // must be last, before saving attributes
         exif_new.saveAttributes();
@@ -3974,32 +4019,6 @@ public class ImageSaver extends Thread {
         }
     }
 
-    /** This fixes a problem when we save from a bitmap - we need to set extra exiftags.
-     *  Exiftool shows these tags as "Date/Time Original" and "Create Date".
-     *  Without these tags, Windows properties for the image doesn't show anything for
-     *  Origin/"Date taken".
-     *  N.B., this is probably redundant on Android 7+, where we'll have transferred these tags
-     *  across from the original JPEG in setExif().
-     */
-    private void setDateTimeExif(ExifInterface exif) {
-        if( MyDebug.LOG )
-            Log.d(TAG, "setDateTimeExif");
-        String exif_datetime = exif.getAttribute(ExifInterface.TAG_DATETIME);
-        if( exif_datetime != null ) {
-            if( MyDebug.LOG ) {
-                Log.d(TAG, "write datetime tags: " + exif_datetime);
-                Log.d(TAG, "TAG_DATETIME_ORIGINAL was: " + exif.getAttribute(ExifInterface.TAG_DATETIME_ORIGINAL));
-                Log.d(TAG, "TAG_DATETIME_DIGITIZED was: " + exif.getAttribute(ExifInterface.TAG_DATETIME_DIGITIZED));
-            }
-            exif.setAttribute(ExifInterface.TAG_DATETIME_ORIGINAL, exif_datetime);
-            exif.setAttribute(ExifInterface.TAG_DATETIME_DIGITIZED, exif_datetime);
-            if( MyDebug.LOG ) {
-                Log.d(TAG, "TAG_DATETIME_ORIGINAL is now: " + exif.getAttribute(ExifInterface.TAG_DATETIME_ORIGINAL));
-                Log.d(TAG, "TAG_DATETIME_DIGITIZED is now: " + exif.getAttribute(ExifInterface.TAG_DATETIME_DIGITIZED));
-            }
-        }
-    }
-
     /** Adds exif tags for datetime from the supplied date, if not present. Needed for camera vendor
      *  extensions which (at least on Galaxy S10e) don't seem to have these tags set at all!
      */
diff --git a/app/src/main/java/net/sourceforge/opencamera/MainActivity.java b/app/src/main/java/net/sourceforge/opencamera/MainActivity.java
index 03df4c929d26b4ad73d468c82c16854f86497273..3d46eddbb516944d944f070e5874d120073f9a96 100644
--- a/app/src/main/java/net/sourceforge/opencamera/MainActivity.java
+++ b/app/src/main/java/net/sourceforge/opencamera/MainActivity.java
@@ -1,16 +1,12 @@
 package net.sourceforge.opencamera;
 
 import android.Manifest;
-import android.animation.ArgbEvaluator;
 import android.animation.ValueAnimator;
 import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
 import android.app.ActivityManager;
 import android.app.AlertDialog;
 import android.app.KeyguardManager;
-import android.app.Notification;
-import android.app.NotificationChannel;
-import android.app.NotificationManager;
 import android.content.ActivityNotFoundException;
 import android.content.ContentResolver;
 import android.content.Context;
@@ -76,6 +72,7 @@ import androidx.annotation.RequiresApi;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.core.content.ContextCompat;
 import androidx.exifinterface.media.ExifInterface;
+import androidx.vectordrawable.graphics.drawable.ArgbEvaluator;
 
 import net.sourceforge.opencamera.camera2.CameraFinder;
 import net.sourceforge.opencamera.camera2.CameraIdentifier;
@@ -148,6 +145,7 @@ public class MainActivity extends AppCompatActivity {
 
     private Preview preview;
     private OrientationEventListener orientationEventListener;
+    private View.OnLayoutChangeListener layoutChangeListener;
     private int large_heap_memory;
     private boolean supports_auto_stabilise;
     private boolean supports_force_video_4k;
@@ -227,9 +225,10 @@ public class MainActivity extends AppCompatActivity {
     public static boolean test_force_supports_camera2; // okay to be static, as this is set for an entire test suite
     public volatile String test_save_settings_file;
 
-    private boolean has_notification;
-    private final String CHANNEL_ID = "open_camera_channel";
-    private final int image_saving_notification_id = 1;
+    // update: notifications now removed due to needing permissions on Android 13+
+    //private boolean has_notification;
+    //private final String CHANNEL_ID = "open_camera_channel";
+    //private final int image_saving_notification_id = 1;
 
     private final float defaultLensZoom = 1.0F;
 
@@ -596,15 +595,50 @@ public class MainActivity extends AppCompatActivity {
         // initialise state of on-screen icons
         mainUI.updateOnScreenIcons();
 
-        // listen for orientation event change
-        orientationEventListener = new OrientationEventListener(this) {
+        if( MainActivity.lock_to_landscape ) {
+            // listen for orientation event change (only required if lock_to_landscape==true
+            // (MainUI.onOrientationChanged() does nothing if lock_to_landscape==false)
+            orientationEventListener = new OrientationEventListener(this) {
+                @Override
+                public void onOrientationChanged(int orientation) {
+                    MainActivity.this.mainUI.onOrientationChanged(orientation);
+                }
+            };
+            if( MyDebug.LOG )
+                Log.d(TAG, "onCreate: time after setting orientation event listener: " + (System.currentTimeMillis() - debug_time));
+        }
+
+        layoutChangeListener = new View.OnLayoutChangeListener() {
             @Override
-            public void onOrientationChanged(int orientation) {
-                MainActivity.this.mainUI.onOrientationChanged(orientation);
+            public void onLayoutChange(View v, int left, int top, int right, int bottom, int oldLeft, int oldTop, int oldRight, int oldBottom) {
+                if( MyDebug.LOG )
+                    Log.d(TAG, "onLayoutChange");
+
+                if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.N && isInMultiWindowMode() ) {
+                    Point display_size = new Point();
+                    Display display = getWindowManager().getDefaultDisplay();
+                    display.getSize(display_size);
+                    if( MyDebug.LOG ) {
+                        Log.d(TAG, "    display width: " + display_size.x);
+                        Log.d(TAG, "    display height: " + display_size.y);
+                        Log.d(TAG, "    layoutUI display width: " + mainUI.layoutUI_display_w);
+                        Log.d(TAG, "    layoutUI display height: " + mainUI.layoutUI_display_h);
+                    }
+                    // We need to call layoutUI when the window is resized without an orientation change -
+                    // this can happen in split-screen or multi-window mode, where onConfigurationChanged
+                    // is not guaranteed to be called.
+                    // We check against the size of when layoutUI was last called, to avoid repeated calls
+                    // when the resize is due to the device rotating and onConfigurationChanged is called -
+                    // in fact we'd have a problem of repeatedly calling layoutUI, since doing layoutUI
+                    // causes onLayoutChange() to be called again.
+                    if( display_size.x != mainUI.layoutUI_display_w || display_size.y != mainUI.layoutUI_display_h ) {
+                        if( MyDebug.LOG )
+                            Log.d(TAG, "call layoutUI due to resize");
+                        mainUI.layoutUI();
+                    }
+                }
             }
         };
-        if( MyDebug.LOG )
-            Log.d(TAG, "onCreate: time after setting orientation event listener: " + (System.currentTimeMillis() - debug_time));
 
         // set up take photo long click
         takePhotoButton.setOnLongClickListener(new View.OnLongClickListener() {
@@ -726,7 +760,7 @@ public class MainActivity extends AppCompatActivity {
                     // E.g., we have a "What's New" for 1.44 (64), but then push out a quick fix for 1.44.1 (65). We don't want to
                     // show the dialog again to people who already received 1.44 (64), but we still want to show the dialog to people
                     // upgrading from earlier versions.
-                    int whats_new_version = 86; // 1.51
+                    int whats_new_version = 88; // 1.52
                     whats_new_version = Math.min(whats_new_version, version_code); // whats_new_version should always be <= version_code, but just in case!
                     if( MyDebug.LOG ) {
                         Log.d(TAG, "whats_new_version: " + whats_new_version);
@@ -786,7 +820,8 @@ public class MainActivity extends AppCompatActivity {
         }).start();
 
         // create notification channel - only needed on Android 8+
-        if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.O ) {
+        // update: notifications now removed due to needing permissions on Android 13+
+        /*if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.O ) {
             CharSequence name = "Open Camera Image Saving";
             String description = "Notification channel for processing and saving images in the background";
             int importance = NotificationManager.IMPORTANCE_LOW;
@@ -796,7 +831,7 @@ public class MainActivity extends AppCompatActivity {
             // or other notification behaviors after this
             NotificationManager notificationManager = getSystemService(NotificationManager.class);
             notificationManager.createNotificationChannel(channel);
-        }
+        }*/
 
         calculateNavigationGap();
 
@@ -1360,6 +1395,17 @@ public class MainActivity extends AppCompatActivity {
         // and we want to avoid notifications hanging around
         cancelImageSavingNotification();
 
+        if( want_no_limits && navigation_gap != 0 ) {
+            if( MyDebug.LOG )
+                Log.d(TAG, "clear FLAG_LAYOUT_NO_LIMITS");
+            // it's unclear why this matters - but there is a bug when exiting split-screen mode, if the split-screen mode had set want_no_limits:
+            // even though the application is created when leaving split-screen mode, we still end up with the window flags for showing
+            // under the navigation bar!
+            // update: this issue is also fixed by not allowing want_no_limits mode in multi-window mode, but still good to reset things here
+            // just in case
+            showUnderNavigation(false);
+        }
+
         // reduce risk of losing any images
         // we don't do this in onPause or onStop, due to risk of ANRs
         // note that even if we did call this earlier in onPause or onStop, we'd still want to wait again here: as it can happen
@@ -1617,7 +1663,10 @@ public class MainActivity extends AppCompatActivity {
 
         mSensorManager.registerListener(accelerometerListener, mSensorAccelerometer, SensorManager.SENSOR_DELAY_NORMAL);
         magneticSensor.registerMagneticListener(mSensorManager);
-        orientationEventListener.enable();
+        if( orientationEventListener != null ) {
+            orientationEventListener.enable();
+        }
+        getWindow().getDecorView().addOnLayoutChangeListener(layoutChangeListener);
 
         // if BLE remote control is enabled, then start the background BLE service
         bluetoothRemoteControl.startRemoteControl();
@@ -1750,7 +1799,10 @@ public class MainActivity extends AppCompatActivity {
         unregisterDisplayListener();
         mSensorManager.unregisterListener(accelerometerListener);
         magneticSensor.unregisterMagneticListener(mSensorManager);
-        orientationEventListener.disable();
+        if( orientationEventListener != null ) {
+            orientationEventListener.disable();
+        }
+        getWindow().getDecorView().removeOnLayoutChangeListener(layoutChangeListener);
         bluetoothRemoteControl.stopRemoteControl();
         freeAudioListener(false);
         //speechControl.stopSpeechRecognizer();
@@ -1807,7 +1859,7 @@ public class MainActivity extends AppCompatActivity {
             if( MyDebug.LOG ) {
                 Log.d(TAG, "onDisplayChanged: " + displayId);
                 Log.d(TAG, "rotation: " + rotation);
-                Log.d(TAG, "old_rotation: " + rotation);
+                Log.d(TAG, "old_rotation: " + old_rotation);
             }
             if( ( rotation == Surface.ROTATION_0 && old_rotation == Surface.ROTATION_180 ) ||
                     ( rotation == Surface.ROTATION_180 && old_rotation == Surface.ROTATION_0 ) ||
@@ -1864,6 +1916,8 @@ public class MainActivity extends AppCompatActivity {
         // n.b., need to call this first, before preview.setCameraDisplayOrientation(), since
         // preview.setCameraDisplayOrientation() will call getDisplayRotation() and we don't want
         // to be using the outdated cached value now that the rotation has changed!
+        // update: no longer relevant, as preview.setCameraDisplayOrientation() now sets
+        // prefer_later to true to avoid using cached value. But might as well call it first anyway.
         resetCachedSystemOrientation();
 
         preview.setCameraDisplayOrientation();
@@ -1992,11 +2046,14 @@ public class MainActivity extends AppCompatActivity {
     }
 
     /** A wrapper for getWindowManager().getDefaultDisplay().getRotation(), except if
-     *  lock_to_landscape==false, this checks for the display being inconsistent with the system
-     *  orientation, and if so, returns a cached value.
+     *  lock_to_landscape==false && prefer_later==false, this uses a cached value.
      */
-    public int getDisplayRotation() {
-        if( lock_to_landscape ) {
+    public int getDisplayRotation(boolean prefer_later) {
+        /*if( MyDebug.LOG ) {
+            Log.d(TAG, "getDisplayRotationDegrees");
+            Log.d(TAG, "prefer_later: " + prefer_later);
+        }*/
+        if( lock_to_landscape || prefer_later ) {
             return getWindowManager().getDefaultDisplay().getRotation();
         }
         // we cache to reduce effect of annoying problem where rotation changes shortly before the
@@ -2398,7 +2455,14 @@ public class MainActivity extends AppCompatActivity {
         if( indx == -1 ) {
             Log.e(TAG, "camera id not in current camera set");
             // this shouldn't happen, but if it does, revert to the first camera id in the set
-            cameraId = camera_set.get(0);
+            // update: oddly had reports of IndexOutOfBoundsException crashes from Google Play from camera_set.get(0)
+            // because of camera_set having length 0, so stick with currCameraId in such cases
+            if( camera_set.size() == 0 ) {
+                Log.e(TAG, "camera_set is empty");
+                cameraId = currCameraId;
+            }
+            else
+                cameraId = camera_set.get(0);
         }
         else {
             indx = (indx+1) % camera_set.size();
@@ -2907,6 +2971,7 @@ public class MainActivity extends AppCompatActivity {
         Bundle bundle = new Bundle();
         bundle.putInt("cameraId", this.preview.getCameraId());
         bundle.putInt("nCameras", preview.getCameraControllerManager().getNumberOfCameras());
+        bundle.putBoolean("camera_open", this.preview.getCameraController() != null);
         bundle.putString("camera_api", this.preview.getCameraAPI());
         bundle.putBoolean("using_android_l", this.preview.usingCamera2API());
         if( this.preview.getCameraController() != null ) {
@@ -3615,18 +3680,81 @@ public class MainActivity extends AppCompatActivity {
                 Log.d(TAG, "set a window insets listener");
             this.set_window_insets_listener = true;
             decorView.getRootView().setOnApplyWindowInsetsListener(new View.OnApplyWindowInsetsListener() {
+                private boolean has_last_system_orientation;
+                private SystemOrientation last_system_orientation;
                 @Override
-                public WindowInsets onApplyWindowInsets(View v, WindowInsets insets) {
+                public @NonNull WindowInsets onApplyWindowInsets(@NonNull View v, @NonNull WindowInsets insets) {
                     if( MyDebug.LOG ) {
+                        Log.d(TAG, "inset left: " + insets.getSystemWindowInsetLeft());
+                        Log.d(TAG, "inset top: " + insets.getSystemWindowInsetTop());
                         Log.d(TAG, "inset right: " + insets.getSystemWindowInsetRight());
                         Log.d(TAG, "inset bottom: " + insets.getSystemWindowInsetBottom());
                     }
-                    if( navigation_gap == 0 ) {
-                        SystemOrientation system_orientation = getSystemOrientation();
-                        boolean system_orientation_portrait = system_orientation == SystemOrientation.PORTRAIT;
-                        navigation_gap = system_orientation_portrait ? insets.getSystemWindowInsetBottom() : insets.getSystemWindowInsetRight();
+                    SystemOrientation system_orientation = getSystemOrientation();
+                    int new_navigation_gap;
+                    switch ( system_orientation ) {
+                        case PORTRAIT:
+                            new_navigation_gap = insets.getSystemWindowInsetBottom();
+                            break;
+                        case LANDSCAPE:
+                            new_navigation_gap = insets.getSystemWindowInsetRight();
+                            break;
+                        case REVERSE_LANDSCAPE:
+                            new_navigation_gap = insets.getSystemWindowInsetLeft();
+                            break;
+                        default:
+                            Log.e(TAG, "unknown system_orientation?!: " + system_orientation);
+                            new_navigation_gap = 0;
+                            break;
+                    }
+
+                    if( has_last_system_orientation && system_orientation != last_system_orientation && new_navigation_gap != navigation_gap ) {
                         if( MyDebug.LOG )
-                            Log.d(TAG, "navigation_gap is " + navigation_gap);
+                            Log.d(TAG, "navigation_gap changed due to system orientation change, from " + navigation_gap + " to " + new_navigation_gap);
+
+                        navigation_gap = new_navigation_gap;
+
+                        if( MyDebug.LOG )
+                            Log.d(TAG, "want_no_limits: " + want_no_limits);
+                        if( want_no_limits ) {
+                            // If we want no_limits mode, then need to take care in case of device orientation
+                            // in cases where that changes the navigation_gap:
+                            // - Need to set showUnderNavigation() (in case navigation_gap when from zero to non-zero or vice versa).
+                            // - Need to call layoutUI() (for different value of navigation_gap)
+
+                            // Need to call showUnderNavigation() from handler for it to take effect.
+                            // Similarly we have problems if we call layoutUI without post-ing it -
+                            // sometimes when rotating a device, we get a call to OnApplyWindowInsetsListener
+                            // with 0 navigation_gap followed by the call with the correct non-zero values -
+                            // posting the call to layoutUI means it runs after the second call, so we have the
+                            // correct navigation_gap.
+                            Handler handler = new Handler();
+                            handler.post(new Runnable() {
+                                @Override
+                                public void run() {
+                                    if( MyDebug.LOG )
+                                        Log.d(TAG, "runnable for change in navigation_gap due to orientation change");
+                                    if( navigation_gap != 0 ) {
+                                        if( MyDebug.LOG )
+                                            Log.d(TAG, "set FLAG_LAYOUT_NO_LIMITS");
+                                        showUnderNavigation(true);
+                                    }
+                                    else {
+                                        if( MyDebug.LOG )
+                                            Log.d(TAG, "clear FLAG_LAYOUT_NO_LIMITS");
+                                        showUnderNavigation(false);
+                                    }
+                                    if( MyDebug.LOG )
+                                        Log.d(TAG, "layout UI due to changing navigation_gap");
+                                    mainUI.layoutUI();
+                                }
+                            });
+                        }
+                    }
+                    else if( navigation_gap == 0 ) {
+                        if( MyDebug.LOG )
+                            Log.d(TAG, "navigation_gap changed from zero to " + new_navigation_gap);
+                        navigation_gap = new_navigation_gap;
                         // Sometimes when this callback is called, the navigation_gap may still be 0 even if
                         // the device doesn't have physical navigation buttons - we need to wait
                         // until we have found a non-zero value before switching to no limits.
@@ -3639,6 +3767,9 @@ public class MainActivity extends AppCompatActivity {
                         }
                     }
 
+                    has_last_system_orientation = true;
+                    last_system_orientation = system_orientation;
+
                     // see comments in MainUI.layoutUI() for why we don't use this
                     /*if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.S && getSystemOrientation() == SystemOrientation.LANDSCAPE ) {
                         Rect privacy_indicator_rect = insets.getPrivacyIndicatorBounds();
@@ -3832,6 +3963,12 @@ public class MainActivity extends AppCompatActivity {
     	}*/
         SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
 
+        if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU ) {
+            // we set this to prevent what's on the preview being used to show under the "recent apps" view - potentially useful
+            // for privacy reasons
+            setRecentsScreenshotEnabled(false);
+        }
+
         if( lock_to_landscape ) {
             // force to landscape mode
             setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
@@ -3925,6 +4062,12 @@ public class MainActivity extends AppCompatActivity {
     public void setWindowFlagsForSettings(boolean set_lock_protect) {
         if( MyDebug.LOG )
             Log.d(TAG, "setWindowFlagsForSettings: " + set_lock_protect);
+
+        if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU ) {
+            // in settings mode, okay to revert to default behaviour for using a screenshot for "recent apps" view
+            setRecentsScreenshotEnabled(true);
+        }
+
         // allow screen rotation
         setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);
 
@@ -4396,7 +4539,7 @@ public class MainActivity extends AppCompatActivity {
                     }
                     gallery_save_anim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                         @Override
-                        public void onAnimationUpdate(ValueAnimator animation) {
+                        public void onAnimationUpdate(@NonNull ValueAnimator animation) {
                             galleryButton.setColorFilter((Integer)animation.getAnimatedValue(), PorterDuff.Mode.MULTIPLY);
                         }
                     });
@@ -4419,21 +4562,22 @@ public class MainActivity extends AppCompatActivity {
             Log.d(TAG, "imageQueueChanged");
         applicationInterface.getDrawPreview().setImageQueueFull( !applicationInterface.canTakeNewPhoto() );
 
-        if( applicationInterface.getImageSaver().getNImagesToSave() == 0) {
+        /*if( applicationInterface.getImageSaver().getNImagesToSave() == 0) {
             cancelImageSavingNotification();
         }
-        else if( has_notification) {
+        else if( has_notification ) {
             // call again to update the text of remaining images
             createImageSavingNotification();
-        }
+        }*/
     }
 
     /** Creates a notification to indicate still saving images (or updates an existing one).
+      * Update: notifications now removed due to needing permissions on Android 13+.
      */
     private void createImageSavingNotification() {
         if( MyDebug.LOG )
             Log.d(TAG, "createImageSavingNotification");
-        if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.O ) {
+        /*if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.O ) {
             int n_images_to_save = applicationInterface.getImageSaver().getNRealImagesToSave();
             Notification.Builder builder = new Notification.Builder(this, CHANNEL_ID)
                     .setSmallIcon(R.drawable.ic_stat_notify_take_photo)
@@ -4446,19 +4590,20 @@ public class MainActivity extends AppCompatActivity {
             NotificationManager notificationManager = getSystemService(NotificationManager.class);
             notificationManager.notify(image_saving_notification_id, builder.build());
             has_notification = true;
-        }
+        }*/
     }
 
     /** Cancels the notification for saving images.
+     *  Update: notifications now removed due to needing permissions on Android 13+.
      */
     private void cancelImageSavingNotification() {
         if( MyDebug.LOG )
             Log.d(TAG, "cancelImageSavingNotification");
-        if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.O ) {
+        /*if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.O ) {
             NotificationManager notificationManager = getSystemService(NotificationManager.class);
             notificationManager.cancel(image_saving_notification_id);
             has_notification = false;
-        }
+        }*/
     }
 
     public void clickedGallery(View view) {
@@ -5255,7 +5400,7 @@ public class MainActivity extends AppCompatActivity {
      */
     private class MyGestureDetector extends SimpleOnGestureListener {
         @Override
-        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
+        public boolean onFling(@NonNull MotionEvent e1, @NonNull MotionEvent e2, float velocityX, float velocityY) {
             try {
                 if( MyDebug.LOG )
                     Log.d(TAG, "from " + e1.getX() + " , " + e1.getY() + " to " + e2.getX() + " , " + e2.getY());
@@ -5284,7 +5429,7 @@ public class MainActivity extends AppCompatActivity {
         }
 
         @Override
-        public boolean onDown(MotionEvent e) {
+        public boolean onDown(@NonNull MotionEvent e) {
             preview.showToast(screen_locked_toast, R.string.screen_is_locked);
             return true;
         }
@@ -5333,7 +5478,16 @@ public class MainActivity extends AppCompatActivity {
 
         boolean old_want_no_limits = want_no_limits;
         this.want_no_limits = false;
-        if( set_window_insets_listener ) {
+        if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.N && isInMultiWindowMode() ) {
+            if( MyDebug.LOG )
+                Log.d(TAG, "multi-window mode");
+            // don't support want_no_limits mode in multi-window mode - extra complexity that the
+            // preview size could change from simply resizing the window; also problem that the
+            // navigation_gap, and whether we'd want want_no_limits, can both change depending on
+            // device orientation (because application can e.g. be in landscape mode even if device
+            // has switched to portrait)
+        }
+        else if( set_window_insets_listener ) {
             Point display_size = new Point();
             Display display = getWindowManager().getDefaultDisplay();
             display.getSize(display_size);
@@ -5365,6 +5519,8 @@ public class MainActivity extends AppCompatActivity {
                             Log.d(TAG, "set FLAG_LAYOUT_NO_LIMITS");
                         showUnderNavigation(true);
                         // need to layout the UI again due to now taking the navigation gap into account
+                        if( MyDebug.LOG )
+                            Log.d(TAG, "layout UI due to changing want_no_limits behaviour");
                         mainUI.layoutUI();
                     }
                     else {
@@ -5378,6 +5534,8 @@ public class MainActivity extends AppCompatActivity {
                     Log.d(TAG, "clear FLAG_LAYOUT_NO_LIMITS");
                 showUnderNavigation(false);
                 // need to layout the UI again due to no longer taking the navigation gap into account
+                if( MyDebug.LOG )
+                    Log.d(TAG, "layout UI due to changing want_no_limits behaviour");
                 mainUI.layoutUI();
             }
         }
@@ -6427,9 +6585,9 @@ public class MainActivity extends AppCompatActivity {
         return this.applicationInterface.hasThumbnailAnimation();
     }
 
-    public boolean testHasNotification() {
+    /*public boolean testHasNotification() {
         return has_notification;
-    }
+    }*/
 }
 
 
diff --git a/app/src/main/java/net/sourceforge/opencamera/MyApplicationInterface.java b/app/src/main/java/net/sourceforge/opencamera/MyApplicationInterface.java
index 4d9cb5b060b74bec8d7c7cc12c3c0122a49f47c8..8c3aa4c1a2c8927223fa0046612137d219c56db5 100644
--- a/app/src/main/java/net/sourceforge/opencamera/MyApplicationInterface.java
+++ b/app/src/main/java/net/sourceforge/opencamera/MyApplicationInterface.java
@@ -1459,13 +1459,14 @@ public class MyApplicationInterface extends BasicApplicationInterface {
     /** Returns the ROTATION_* enum of the display relative to the natural device orientation, but
      *  also checks for the preview being rotated due to user preference
      *  RotatePreviewPreferenceKey.
+     *  See ApplicationInterface.getDisplayRotation() for more details, including for prefer_later.
      */
     @Override
-    public int getDisplayRotation() {
+    public int getDisplayRotation(boolean prefer_later) {
         // important to use cached rotation to reduce issues of incorrect focus square location when
         // rotating device, due to strange Android behaviour where rotation changes shortly before
         // the configuration actually changes
-        int rotation = main_activity.getDisplayRotation();
+        int rotation = main_activity.getDisplayRotation(prefer_later);
 
         String rotate_preview = sharedPreferences.getString(PreferenceKeys.RotatePreviewPreferenceKey, "0");
         if( MyDebug.LOG )
@@ -1838,9 +1839,12 @@ public class MyApplicationInterface extends BasicApplicationInterface {
 
     @Override
     public boolean allowZoom() {
-        if( getPhotoMode() == PhotoMode.Panorama || isCameraExtensionPref() ) {
+        if( getPhotoMode() == PhotoMode.Panorama ) {
             // don't allow zooming in panorama mode, the algorithm isn't set up to support this!
-            // zoom also not supported for camera extensions
+            return false;
+        }
+        else if( isCameraExtensionPref() && Build.VERSION.SDK_INT >= Build.VERSION_CODES.S &&  !main_activity.getPreview().supportsZoomForCameraExtension(getCameraExtensionPref()) ) {
+            // zoom not supported for camera extension
             return false;
         }
         return true;
@@ -1989,10 +1993,11 @@ public class MyApplicationInterface extends BasicApplicationInterface {
                 if( MyDebug.LOG )
                     Log.d(TAG, "TargetCallback.onTooFar");
 
-                if( !main_activity.is_test ) {
+                // it's better not to cancel the panorama if the user moves the device too far in wrong direction
+                /*if( !main_activity.is_test ) {
                     main_activity.getPreview().showToast(null, R.string.panorama_cancelled, true);
                     MyApplicationInterface.this.stopPanorama(true);
-                }
+                }*/
             }
 
         });
diff --git a/app/src/main/java/net/sourceforge/opencamera/MyPreferenceFragment.java b/app/src/main/java/net/sourceforge/opencamera/MyPreferenceFragment.java
index 677f69f219ad0a94625205b72d7d08d5c74ca656..0aa5ca669beb5a3d41e33b2399ef7687fae08363 100644
--- a/app/src/main/java/net/sourceforge/opencamera/MyPreferenceFragment.java
+++ b/app/src/main/java/net/sourceforge/opencamera/MyPreferenceFragment.java
@@ -107,6 +107,10 @@ public class MyPreferenceFragment extends PreferenceFragment implements OnShared
         if( MyDebug.LOG )
             Log.d(TAG, "nCameras: " + nCameras);
 
+        final boolean camera_open = bundle.getBoolean("camera_open");
+        if( MyDebug.LOG )
+            Log.d(TAG, "camera_open: " + camera_open);
+
         final String camera_api = bundle.getString("camera_api");
 
         final String photo_mode_string = bundle.getString("photo_mode_string");
@@ -155,7 +159,11 @@ public class MyPreferenceFragment extends PreferenceFragment implements OnShared
         }
         if( MyDebug.LOG )
             Log.d(TAG, "has_antibanding?: " + has_antibanding);
-        if( !has_antibanding ) {
+        if( !has_antibanding && ( camera_open || sharedPreferences.getString(PreferenceKeys.AntiBandingPreferenceKey, CameraController.ANTIBANDING_DEFAULT).equals(CameraController.ANTIBANDING_DEFAULT) ) ) {
+            // if camera not open, we'll think this setting isn't supported - but should only remove
+            // this preference if it's set to the default (otherwise if user sets to a non-default
+            // value that causes camera to not open, user won't be able to put it back to the
+            // default!)
             Preference pref = findPreference(PreferenceKeys.AntiBandingPreferenceKey);
             PreferenceGroup pg = (PreferenceGroup)this.findPreference("preference_screen_processing_settings");
             pg.removePreference(pref);
@@ -172,7 +180,11 @@ public class MyPreferenceFragment extends PreferenceFragment implements OnShared
         }
         if( MyDebug.LOG )
             Log.d(TAG, "has_edge_mode?: " + has_edge_mode);
-        if( !has_edge_mode ) {
+        if( !has_edge_mode && ( camera_open || sharedPreferences.getString(PreferenceKeys.EdgeModePreferenceKey, CameraController.EDGE_MODE_DEFAULT).equals(CameraController.EDGE_MODE_DEFAULT) ) ) {
+            // if camera not open, we'll think this setting isn't supported - but should only remove
+            // this preference if it's set to the default (otherwise if user sets to a non-default
+            // value that causes camera to not open, user won't be able to put it back to the
+            // default!)
             Preference pref = findPreference(PreferenceKeys.EdgeModePreferenceKey);
             PreferenceGroup pg = (PreferenceGroup)this.findPreference("preference_screen_processing_settings");
             pg.removePreference(pref);
@@ -189,7 +201,11 @@ public class MyPreferenceFragment extends PreferenceFragment implements OnShared
         }
         if( MyDebug.LOG )
             Log.d(TAG, "has_noise_reduction_mode?: " + has_noise_reduction_mode);
-        if( !has_noise_reduction_mode ) {
+        if( !has_noise_reduction_mode && ( camera_open || sharedPreferences.getString(PreferenceKeys.CameraNoiseReductionModePreferenceKey, CameraController.NOISE_REDUCTION_MODE_DEFAULT).equals(CameraController.NOISE_REDUCTION_MODE_DEFAULT) ) ) {
+            // if camera not open, we'll think this setting isn't supported - but should only remove
+            // this preference if it's set to the default (otherwise if user sets to a non-default
+            // value that causes camera to not open, user won't be able to put it back to the
+            // default!)
             Preference pref = findPreference(PreferenceKeys.CameraNoiseReductionModePreferenceKey);
             PreferenceGroup pg = (PreferenceGroup)this.findPreference("preference_screen_processing_settings");
             pg.removePreference(pref);
@@ -199,8 +215,12 @@ public class MyPreferenceFragment extends PreferenceFragment implements OnShared
         if( MyDebug.LOG )
             Log.d(TAG, "supports_face_detection: " + supports_face_detection);
 
-        if( !supports_face_detection ) {
-            Preference pref = findPreference("preference_face_detection");
+        if( !supports_face_detection  && ( camera_open || sharedPreferences.getBoolean(PreferenceKeys.FaceDetectionPreferenceKey, false) == false ) ) {
+            // if camera not open, we'll think this setting isn't supported - but should only remove
+            // this preference if it's set to the default (otherwise if user sets to a non-default
+            // value that causes camera to not open, user won't be able to put it back to the
+            // default!)
+            Preference pref = findPreference(PreferenceKeys.FaceDetectionPreferenceKey);
             PreferenceGroup pg = (PreferenceGroup)this.findPreference("preference_category_camera_controls");
             pg.removePreference(pref);
 
@@ -741,12 +761,17 @@ public class MyPreferenceFragment extends PreferenceFragment implements OnShared
             Log.d(TAG, "tonemap_max_curve_points: " + tonemap_max_curve_points);
             Log.d(TAG, "supports_tonemap_curve: " + supports_tonemap_curve);
         }
-        if( !supports_tonemap_curve ) {
-            Preference pref = findPreference("preference_video_log");
+        if( !supports_tonemap_curve && ( camera_open || sharedPreferences.getString(PreferenceKeys.VideoLogPreferenceKey, "off").equals("off") ) ) {
+            // if camera not open, we'll think this setting isn't supported - but should only remove
+            // this preference if it's set to the default (otherwise if user sets to a non-default
+            // value that causes camera to not open, user won't be able to put it back to the
+            // default!)
+            // (needed for Pixel 6 Pro where setting to sRGB causes camera to fail to open when in video mode)
+            Preference pref = findPreference(PreferenceKeys.VideoLogPreferenceKey);
             PreferenceGroup pg = (PreferenceGroup)this.findPreference("preference_screen_video_settings");
             pg.removePreference(pref);
 
-            pref = findPreference("preference_video_profile_gamma");
+            pref = findPreference(PreferenceKeys.VideoProfileGammaPreferenceKey);
             pg = (PreferenceGroup)this.findPreference("preference_screen_video_settings");
             pg.removePreference(pref);
         }
diff --git a/app/src/main/java/net/sourceforge/opencamera/MyTileService.java b/app/src/main/java/net/sourceforge/opencamera/MyTileService.java
index 11e3eb428cda0db2c02e07f119777e1a8754d971..c2a0eb4525a85dac6eeecd78041442629e100b04 100644
--- a/app/src/main/java/net/sourceforge/opencamera/MyTileService.java
+++ b/app/src/main/java/net/sourceforge/opencamera/MyTileService.java
@@ -47,6 +47,6 @@ public class MyTileService extends TileService {
         Intent intent = new Intent(this, MainActivity.class);
         intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
         intent.setAction(TILE_ID);
-        startActivityAndCollapse(intent);
+        startActivityAndCollapse(intent); // use this instead of startActivity() so that the notification panel doesn't remain pulled down
     }
 }
diff --git a/app/src/main/java/net/sourceforge/opencamera/MyTileServiceFrontCamera.java b/app/src/main/java/net/sourceforge/opencamera/MyTileServiceFrontCamera.java
index ca92cb3e24eed82d2319b237ac7318464255511d..7d464387ea8c0f57ee8d14b557d19b645cae78bd 100644
--- a/app/src/main/java/net/sourceforge/opencamera/MyTileServiceFrontCamera.java
+++ b/app/src/main/java/net/sourceforge/opencamera/MyTileServiceFrontCamera.java
@@ -47,6 +47,6 @@ public class MyTileServiceFrontCamera extends TileService {
         Intent intent = new Intent(this, MainActivity.class);
         intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
         intent.setAction(TILE_ID);
-        startActivityAndCollapse(intent);
+        startActivityAndCollapse(intent); // use this instead of startActivity() so that the notification panel doesn't remain pulled down
     }
 }
diff --git a/app/src/main/java/net/sourceforge/opencamera/MyTileServiceVideo.java b/app/src/main/java/net/sourceforge/opencamera/MyTileServiceVideo.java
index b7a6789f490da7a1746ee760c8baa3ed660a6217..6b3a0d37ccede7ec5a8047fa3a93798dd8231c78 100644
--- a/app/src/main/java/net/sourceforge/opencamera/MyTileServiceVideo.java
+++ b/app/src/main/java/net/sourceforge/opencamera/MyTileServiceVideo.java
@@ -47,6 +47,6 @@ public class MyTileServiceVideo extends TileService {
         Intent intent = new Intent(this, MainActivity.class);
         intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
         intent.setAction(TILE_ID);
-        startActivityAndCollapse(intent);
+        startActivityAndCollapse(intent); // use this instead of startActivity() so that the notification panel doesn't remain pulled down
     }
 }
diff --git a/app/src/main/java/net/sourceforge/opencamera/PanoramaProcessor.java b/app/src/main/java/net/sourceforge/opencamera/PanoramaProcessor.java
index 1a3f2c1903a452c5b807715bb9e76ecb5f26dd4f..5f4e40660a923039b794162a4c3aa5ad5cd91ef3 100644
--- a/app/src/main/java/net/sourceforge/opencamera/PanoramaProcessor.java
+++ b/app/src/main/java/net/sourceforge/opencamera/PanoramaProcessor.java
@@ -229,10 +229,10 @@ public class PanoramaProcessor {
         if( MyDebug.LOG )
             Log.d(TAG, "### createLaplacianPyramid: time after createGaussianPyramid: " + (System.currentTimeMillis() - time_s));
         /*if( MyDebug.LOG )
-		{
-			// debug
-			savePyramid("gaussian", gaussianPyramid);
-		}*/
+        {
+            // debug
+            savePyramid("gaussian", gaussianPyramid);
+        }*/
         List<Allocation> pyramid = new ArrayList<>();
 
         for(int i=0;i<gaussianPyramid.size()-1;i++) {
@@ -249,19 +249,19 @@ public class PanoramaProcessor {
                 Log.d(TAG, "next_gauss_expanded: " + next_gauss_expanded.getType().getX() + " , " + next_gauss_expanded.getType().getY());
             }
             /*if( MyDebug.LOG )
-			{
-				// debug
-				saveAllocation(name + "_this_gauss_" + i + ".jpg", this_gauss);
-				saveAllocation(name + "_next_gauss_expanded_" + i + ".jpg", next_gauss_expanded);
-			}*/
+            {
+                // debug
+                saveAllocation(name + "_this_gauss_" + i + ".jpg", this_gauss);
+                saveAllocation(name + "_next_gauss_expanded_" + i + ".jpg", next_gauss_expanded);
+            }*/
             Allocation difference = subtractBitmap(script, this_gauss, next_gauss_expanded);
             if( MyDebug.LOG )
                 Log.d(TAG, "### createLaplacianPyramid: time after subtractBitmap for level " + i + ": " + (System.currentTimeMillis() - time_s));
             /*if( MyDebug.LOG )
-			{
-				// debug
-				saveAllocation(name + "_difference_" + i + ".jpg", difference);
-			}*/
+            {
+                // debug
+                saveAllocation(name + "_difference_" + i + ".jpg", difference);
+            }*/
             pyramid.add(difference);
             //pyramid.add(this_gauss);
 
@@ -712,21 +712,21 @@ public class PanoramaProcessor {
 
         // debug
         /*if( MyDebug.LOG )
-		{
-			savePyramid("lhs_laplacian", lhs_pyramid);
-			savePyramid("rhs_laplacian", rhs_pyramid);
-		}*/
+        {
+            savePyramid("lhs_laplacian", lhs_pyramid);
+            savePyramid("rhs_laplacian", rhs_pyramid);
+        }*/
 
         // debug
         /*if( MyDebug.LOG )
-		{
-			Bitmap lhs_collapsed = collapseLaplacianPyramid(script, lhs_pyramid);
-			saveBitmap(lhs_collapsed, "lhs_collapsed.jpg");
-			Bitmap rhs_collapsed = collapseLaplacianPyramid(script, rhs_pyramid);
-			saveBitmap(rhs_collapsed, "rhs_collapsed.jpg");
-			lhs_collapsed.recycle();
-			rhs_collapsed.recycle();
-		}*/
+        {
+            Bitmap lhs_collapsed = collapseLaplacianPyramid(script, lhs_pyramid);
+            saveBitmap(lhs_collapsed, "lhs_collapsed.jpg");
+            Bitmap rhs_collapsed = collapseLaplacianPyramid(script, rhs_pyramid);
+            saveBitmap(rhs_collapsed, "rhs_collapsed.jpg");
+            lhs_collapsed.recycle();
+            rhs_collapsed.recycle();
+        }*/
 
         mergePyramids(pyramidBlendingScript, lhs_pyramid, rhs_pyramid, best_path, best_path_n_x);
         if( MyDebug.LOG )
@@ -764,12 +764,12 @@ public class PanoramaProcessor {
         @Override
         public int compareTo(FeatureMatch that) {
             //return (int)(this.distance - that.distance);
-				/*if( this.distance > that.distance )
-					return 1;
-				else if( this.distance < that.distance )
-					return -1;
-				else
-					return 0;*/
+                /*if( this.distance > that.distance )
+                    return 1;
+                else if( this.distance < that.distance )
+                    return -1;
+                else
+                    return 0;*/
             return Float.compare(this.distance, that.distance);
         }
 
@@ -785,21 +785,21 @@ public class PanoramaProcessor {
         for(int indx=st_indx;indx<nd_indx;indx++) {
             FeatureMatch match = matches.get(indx);
 
-				/*float distance = 0;
-				for(int dy=-feature_descriptor_radius;dy<=feature_descriptor_radius;dy++) {
-					for(int dx=-feature_descriptor_radius;dx<=feature_descriptor_radius;dx++) {
-						int pixel0 = bitmaps.get(0).getPixel(point0.x + dx, point0.y + dy);
-						int pixel1 = bitmaps.get(1).getPixel(point1.x + dx, point1.y + dy);
-						//int value0 = (Color.red(pixel0) + Color.green(pixel0) + Color.blue(pixel0))/3;
-						//int value1 = (Color.red(pixel1) + Color.green(pixel1) + Color.blue(pixel1))/3;
-						int value0 = (int)(0.3*Color.red(pixel0) + 0.59*Color.green(pixel0) + 0.11*Color.blue(pixel0));
-						int value1 = (int)(0.3*Color.red(pixel1) + 0.59*Color.green(pixel1) + 0.11*Color.blue(pixel1));
-						int dist2 = value0*value0 + value1+value1;
-						distance += ((float)dist2)/65025.0f; // so distance for a given pixel is from 0 to 1
-					}
-				}
-				distance /= (float)wid2; // normalise from 0 to 1
-				match.distance = distance;*/
+                /*float distance = 0;
+                for(int dy=-feature_descriptor_radius;dy<=feature_descriptor_radius;dy++) {
+                    for(int dx=-feature_descriptor_radius;dx<=feature_descriptor_radius;dx++) {
+                        int pixel0 = bitmaps.get(0).getPixel(point0.x + dx, point0.y + dy);
+                        int pixel1 = bitmaps.get(1).getPixel(point1.x + dx, point1.y + dy);
+                        //int value0 = (Color.red(pixel0) + Color.green(pixel0) + Color.blue(pixel0))/3;
+                        //int value1 = (Color.red(pixel1) + Color.green(pixel1) + Color.blue(pixel1))/3;
+                        int value0 = (int)(0.3*Color.red(pixel0) + 0.59*Color.green(pixel0) + 0.11*Color.blue(pixel0));
+                        int value1 = (int)(0.3*Color.red(pixel1) + 0.59*Color.green(pixel1) + 0.11*Color.blue(pixel1));
+                        int dist2 = value0*value0 + value1+value1;
+                        distance += ((float)dist2)/65025.0f; // so distance for a given pixel is from 0 to 1
+                    }
+                }
+                distance /= (float)wid2; // normalise from 0 to 1
+                match.distance = distance;*/
 
             float fsum = 0, gsum = 0;
             float f2sum = 0, g2sum = 0;
@@ -845,12 +845,12 @@ public class PanoramaProcessor {
             float g_recip = gden==0 ? 0.0f : 1/ gden;
             float fg_corr = wid2*fgsum-fsum*gsum;
             //if( MyDebug.LOG ) {
-            //	Log.d(TAG, "match distance: ");
-            //	Log.d(TAG, "    fg_corr: " + fg_corr);
-            //	Log.d(TAG, "    fden: " + fden);
-            //	Log.d(TAG, "    gden: " + gden);
-            //	Log.d(TAG, "    f_recip: " + f_recip);
-            //	Log.d(TAG, "    g_recip: " + g_recip);
+            //  Log.d(TAG, "match distance: ");
+            //  Log.d(TAG, "    fg_corr: " + fg_corr);
+            //  Log.d(TAG, "    fden: " + fden);
+            //  Log.d(TAG, "    gden: " + gden);
+            //  Log.d(TAG, "    f_recip: " + f_recip);
+            //  Log.d(TAG, "    g_recip: " + g_recip);
             //}
             // negate, as we want it so that lower value means better match, and normalise to 0-1
             match.distance = 1.0f-Math.abs((fg_corr*fg_corr*f_recip*g_recip));
@@ -867,6 +867,7 @@ public class PanoramaProcessor {
         private final int [] pixels1;
 
         ComputeDistancesBetweenMatchesThread(List<FeatureMatch> matches, int st_indx, int nd_indx, int feature_descriptor_radius, List<Bitmap> bitmaps, int [] pixels0, int [] pixels1) {
+            super("ComputeDistancesBetweenMatchesThread");
             this.matches = matches;
             this.st_indx = st_indx;
             this.nd_indx = nd_indx;
@@ -921,7 +922,7 @@ public class PanoramaProcessor {
             Log.d(TAG, "### autoAlignmentByFeature: time after creating allocations: " + (System.currentTimeMillis() - time_s));
 
         // create RenderScript
-		if( featureDetectorScript == null ) {
+        if( featureDetectorScript == null ) {
             featureDetectorScript = new ScriptC_feature_detector(rs);
         }
         if( MyDebug.LOG )
@@ -953,15 +954,15 @@ public class PanoramaProcessor {
             featureDetectorScript.set_bitmap_Iy(iy_allocation);
             featureDetectorScript.forEach_compute_derivatives(gs_allocation);
 
-			/*if( MyDebug.LOG ) {
-				// debugging
+            /*if( MyDebug.LOG ) {
+                // debugging
                 byte [] bytes_x = new byte[width*height];
                 byte [] bytes_y = new byte[width*height];
                 ix_allocation.copyTo(bytes_x);
                 iy_allocation.copyTo(bytes_y);
                 int [] pixels_x = new int[width*height];
                 int [] pixels_y = new int[width*height];
-				for(int j=0;j<width*height;j++) {
+                for(int j=0;j<width*height;j++) {
                     int b = bytes_x[j];
                     if( b < 0 )
                         b += 255;
@@ -970,30 +971,30 @@ public class PanoramaProcessor {
                     if( b < 0 )
                         b += 255;
                     pixels_y[j] = Color.argb(255, b, b, b);
-				}
+                }
                 Bitmap bitmap_x = Bitmap.createBitmap(pixels_x, width, height, Bitmap.Config.ARGB_8888);
                 Bitmap bitmap_y = Bitmap.createBitmap(pixels_y, width, height, Bitmap.Config.ARGB_8888);
                 File file_x = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM) + "/ix_bitmap" + debug_index + "_" + i + ".png");
                 File file_y = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM) + "/iy_bitmap" + debug_index + "_" + i + ".png");
-				try {
+                try {
                     MainActivity mActivity = (MainActivity) context;
 
-					OutputStream outputStream = new FileOutputStream(file_x);
-					bitmap_x.compress(Bitmap.CompressFormat.PNG, 100, outputStream);
-					outputStream.close();
-					mActivity.getStorageUtils().broadcastFile(file_x, true, false, true);
+                    OutputStream outputStream = new FileOutputStream(file_x);
+                    bitmap_x.compress(Bitmap.CompressFormat.PNG, 100, outputStream);
+                    outputStream.close();
+                    mActivity.getStorageUtils().broadcastFile(file_x, true, false, true);
 
                     outputStream = new FileOutputStream(file_y);
                     bitmap_y.compress(Bitmap.CompressFormat.PNG, 100, outputStream);
                     outputStream.close();
                     mActivity.getStorageUtils().broadcastFile(file_y, true, false, true);
-				}
-				catch(IOException e) {
-					e.printStackTrace();
-				}
+                }
+                catch(IOException e) {
+                    e.printStackTrace();
+                }
                 bitmap_x.recycle();
                 bitmap_y.recycle();
-			}*/
+            }*/
 
             if( MyDebug.LOG )
                 Log.d(TAG, "call corner detector script for image: " + i);
@@ -1003,45 +1004,45 @@ public class PanoramaProcessor {
             featureDetectorScript.set_bitmap_Iy(iy_allocation);
             featureDetectorScript.forEach_corner_detector(gs_allocation, strength_allocation);
 
-			/*if( MyDebug.LOG ) {
-				// debugging
-				float [] bytes = new float[width*height];
-				strength_allocation.copyTo(bytes);
-				int [] pixels = new int[width*height];
-				float max_value = 0.0f;
-				for(int j=0;j<width*height;j++) {
-					if( bytes[j] < 1.0f )
-						bytes[j] = 0.0f;
-					else
-						bytes[j] = (float)Math.log10(bytes[j]);
-					if( bytes[j] > max_value )
-						max_value = bytes[j];
-				}
-				if( MyDebug.LOG )
-					Log.d(TAG, "strength max_value: " + max_value);
-				for(int j=0;j<width*height;j++) {
-					float value = bytes[j]/max_value;
-					int c = (int)(255.0f*value+0.5f);
-					if( c > 255 )
-						c = 255;
-					else if( c < 0 )
-						c = 0;
-					pixels[j] = Color.argb(255, c, c, c);
-				}
-				Bitmap bitmap = Bitmap.createBitmap(pixels, width, height, Bitmap.Config.ARGB_8888);
-				File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM) + "/corner_strength_bitmap" + debug_index + "_" + i + ".jpg");
-				try {
-					OutputStream outputStream = new FileOutputStream(file);
-					bitmap.compress(Bitmap.CompressFormat.JPEG, 90, outputStream);
-					outputStream.close();
-					MainActivity mActivity = (MainActivity) context;
-					mActivity.getStorageUtils().broadcastFile(file, true, false, true);
-				}
-				catch(IOException e) {
-					e.printStackTrace();
-				}
-				bitmap.recycle();
-			}*/
+            /*if( MyDebug.LOG ) {
+                // debugging
+                float [] bytes = new float[width*height];
+                strength_allocation.copyTo(bytes);
+                int [] pixels = new int[width*height];
+                float max_value = 0.0f;
+                for(int j=0;j<width*height;j++) {
+                    if( bytes[j] < 1.0f )
+                        bytes[j] = 0.0f;
+                    else
+                        bytes[j] = (float)Math.log10(bytes[j]);
+                    if( bytes[j] > max_value )
+                        max_value = bytes[j];
+                }
+                if( MyDebug.LOG )
+                    Log.d(TAG, "strength max_value: " + max_value);
+                for(int j=0;j<width*height;j++) {
+                    float value = bytes[j]/max_value;
+                    int c = (int)(255.0f*value+0.5f);
+                    if( c > 255 )
+                        c = 255;
+                    else if( c < 0 )
+                        c = 0;
+                    pixels[j] = Color.argb(255, c, c, c);
+                }
+                Bitmap bitmap = Bitmap.createBitmap(pixels, width, height, Bitmap.Config.ARGB_8888);
+                File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM) + "/corner_strength_bitmap" + debug_index + "_" + i + ".jpg");
+                try {
+                    OutputStream outputStream = new FileOutputStream(file);
+                    bitmap.compress(Bitmap.CompressFormat.JPEG, 90, outputStream);
+                    outputStream.close();
+                    MainActivity mActivity = (MainActivity) context;
+                    mActivity.getStorageUtils().broadcastFile(file, true, false, true);
+                }
+                catch(IOException e) {
+                    e.printStackTrace();
+                }
+                bitmap.recycle();
+            }*/
 
             ix_allocation.destroy();
             //noinspection UnusedAssignment
@@ -1057,26 +1058,26 @@ public class PanoramaProcessor {
             //noinspection UnusedAssignment
             gs_allocation = null;
 
-			/*featureDetectorScript.set_corner_threshold(100000000.0f);
-			featureDetectorScript.set_bitmap(strength_allocation);
-			featureDetectorScript.forEach_local_maximum(strength_allocation, local_max_features_allocation);
-			// collect points
-			byte [] bytes = new byte[width*height];
-			local_max_features_allocation.copyTo(bytes);
-			// find points
-			List<Point> points = new ArrayList<>();
-			for(int y=feature_descriptor_radius;y<height-feature_descriptor_radius;y++) {
-				for(int x=feature_descriptor_radius;x<width-feature_descriptor_radius;x++) {
-					int j = y*width + x;
-					// remember, bytes are signed!
-					if( bytes[j] != 0 ) {
-						Point point = new Point(x, y);
-						points.add(point);
-					}
-				}
-			}
-			points_arrays[i] = points.toArray(new Point[0]);
-			*/
+            /*featureDetectorScript.set_corner_threshold(100000000.0f);
+            featureDetectorScript.set_bitmap(strength_allocation);
+            featureDetectorScript.forEach_local_maximum(strength_allocation, local_max_features_allocation);
+            // collect points
+            byte [] bytes = new byte[width*height];
+            local_max_features_allocation.copyTo(bytes);
+            // find points
+            List<Point> points = new ArrayList<>();
+            for(int y=feature_descriptor_radius;y<height-feature_descriptor_radius;y++) {
+                for(int x=feature_descriptor_radius;x<width-feature_descriptor_radius;x++) {
+                    int j = y*width + x;
+                    // remember, bytes are signed!
+                    if( bytes[j] != 0 ) {
+                        Point point = new Point(x, y);
+                        points.add(point);
+                    }
+                }
+            }
+            points_arrays[i] = points.toArray(new Point[0]);
+            */
 
             featureDetectorScript.set_bitmap(strength_allocation);
             //final int n_y_chunks = 1;
@@ -1157,12 +1158,12 @@ public class PanoramaProcessor {
                             threshold = 0.5f * ( low_threshold + threshold );
                             if( MyDebug.LOG )
                                 Log.d(TAG, "    reduced threshold to: " + threshold);
-							/*if( low_threshold == 0.0f ) {
-								throw new RuntimeException();
-							}*/
-							/*if( count == 0 ) {
-								throw new RuntimeException();
-							}*/
+                            /*if( low_threshold == 0.0f ) {
+                                throw new RuntimeException();
+                            }*/
+                            /*if( count == 0 ) {
+                                throw new RuntimeException();
+                            }*/
                         }
                     }
                     else if( count+1 == max_iter ) {
@@ -1208,8 +1209,8 @@ public class PanoramaProcessor {
         if( points_arrays[0].length < min_required_corners || points_arrays[1].length < min_required_corners ) {
             if( MyDebug.LOG )
                 Log.d(TAG, "too few points!");
-			/*if( true )
-				throw new RuntimeException();*/
+            /*if( true )
+                throw new RuntimeException();*/
 
             // free allocations
             for(int i=0;i<allocations.length;i++) {
@@ -1321,10 +1322,10 @@ public class PanoramaProcessor {
             }
             else {
                 int st_indx = 0, nd_indx = matches.size();
-				/*final int wid = 2*feature_descriptor_radius+1;
-				final int wid2 = wid*wid;
-				int [] pixels0 = new int[wid2];
-				int [] pixels1 = new int[wid2];*/
+                /*final int wid = 2*feature_descriptor_radius+1;
+                final int wid2 = wid*wid;
+                int [] pixels0 = new int[wid2];
+                int [] pixels1 = new int[wid2];*/
                 computeDistancesBetweenMatches(matches, st_indx, nd_indx, feature_descriptor_radius, bitmaps, pixels0, pixels1);
             }
         }
@@ -1388,10 +1389,10 @@ public class PanoramaProcessor {
             actual_matches.add(match);
             has_matched0[match.index0] = true;
             has_matched1[match.index1] = true;
-			/*if( actual_matches.size() == n_matches ) {
-				// only use best matches
-				break;
-			}*/
+            /*if( actual_matches.size() == n_matches ) {
+                // only use best matches
+                break;
+            }*/
         }
         if( MyDebug.LOG )
             Log.d(TAG, "### autoAlignmentByFeature: time after initial matching: " + (System.currentTimeMillis() - time_s));
@@ -1431,8 +1432,8 @@ public class PanoramaProcessor {
         if( actual_matches.size() == 0 ) {
             if( MyDebug.LOG )
                 Log.d(TAG, "no matches!");
-			/*if( true )
-				throw new RuntimeException();*/
+            /*if( true )
+                throw new RuntimeException();*/
 
             // free allocations
             for(int i=0;i<allocations.length;i++) {
@@ -1556,18 +1557,18 @@ public class PanoramaProcessor {
                             continue;
                         }
 
-						/*float y_scale = 1.0f;
-						boolean found_y_scale = false;
-						if( estimate_y_scale && Math.abs(dy0) > min_rotation_dist && Math.abs(dy1) > min_rotation_dist ) {
-							y_scale = dy1 / dy0;
-							if( y_scale <= max_y_scale && y_scale >= 1.0f/max_y_scale ) {
-								found_y_scale = true;
-							}
-							else {
-								y_scale = 1.0f;
-							}
-							dy0 *= y_scale;
-						}*/
+                        /*float y_scale = 1.0f;
+                        boolean found_y_scale = false;
+                        if( estimate_y_scale && Math.abs(dy0) > min_rotation_dist && Math.abs(dy1) > min_rotation_dist ) {
+                            y_scale = dy1 / dy0;
+                            if( y_scale <= max_y_scale && y_scale >= 1.0f/max_y_scale ) {
+                                found_y_scale = true;
+                            }
+                            else {
+                                y_scale = 1.0f;
+                            }
+                            dy0 *= y_scale;
+                        }*/
 
                         float angle = (float)(Math.atan2(dy1, dx1) - Math.atan2(dy0, dx0));
                         if( angle < -Math.PI )
@@ -1578,17 +1579,17 @@ public class PanoramaProcessor {
                             // reject too large angles
                             continue;
                         }
-						/*if( MyDebug.LOG ) {
-							Log.d(TAG, "ransac: " + i + " , " + j + ": ");
-							Log.d(TAG, "    match 0: " + points_arrays[0][match.index0].x + " , " + points_arrays[0][match.index0].y);
-							Log.d(TAG, "    match 1: " + points_arrays[1][match.index1].x + " , " + points_arrays[1][match.index1].y);
-							Log.d(TAG, "    match2 0: " + points_arrays[0][match2.index0].x + " , " + points_arrays[0][match2.index0].y);
-							Log.d(TAG, "    match2 1: " + points_arrays[1][match2.index1].x + " , " + points_arrays[1][match2.index1].y);
-							Log.d(TAG, "    y_scale: " + y_scale);
-							Log.d(TAG, "    angle: " + angle);
-							Log.d(TAG, "    mag0: " + Math.sqrt(mag_sq0));
-							Log.d(TAG, "    mag1: " + Math.sqrt(mag_sq1));
-						}*/
+                        /*if( MyDebug.LOG ) {
+                            Log.d(TAG, "ransac: " + i + " , " + j + ": ");
+                            Log.d(TAG, "    match 0: " + points_arrays[0][match.index0].x + " , " + points_arrays[0][match.index0].y);
+                            Log.d(TAG, "    match 1: " + points_arrays[1][match.index1].x + " , " + points_arrays[1][match.index1].y);
+                            Log.d(TAG, "    match2 0: " + points_arrays[0][match2.index0].x + " , " + points_arrays[0][match2.index0].y);
+                            Log.d(TAG, "    match2 1: " + points_arrays[1][match2.index1].x + " , " + points_arrays[1][match2.index1].y);
+                            Log.d(TAG, "    y_scale: " + y_scale);
+                            Log.d(TAG, "    angle: " + angle);
+                            Log.d(TAG, "    mag0: " + Math.sqrt(mag_sq0));
+                            Log.d(TAG, "    mag1: " + Math.sqrt(mag_sq1));
+                        }*/
 
                         float y_scale = 1.0f;
                         boolean found_y_scale = false;
@@ -1624,12 +1625,12 @@ public class PanoramaProcessor {
 
                             float dx = transformed_x0 - x1;
                             float dy = transformed_y0 - y1;
-							/*if( MyDebug.LOG ) {
-								if( other_match == match )
-									Log.d(TAG, "    ransac on match: " + i + " , " + j + " : " + dx + " , " + dy);
-								else if( other_match == match2 )
-									Log.d(TAG, "    ransac on match2: " + i + " , " + j + " : " + dx + " , " + dy);
-							}*/
+                            /*if( MyDebug.LOG ) {
+                                if( other_match == match )
+                                    Log.d(TAG, "    ransac on match: " + i + " , " + j + " : " + dx + " , " + dy);
+                                else if( other_match == match2 )
+                                    Log.d(TAG, "    ransac on match2: " + i + " , " + j + " : " + dx + " , " + dy);
+                            }*/
                             float error2 = dx*dx + dy*dy;
                             if( error2 + 1.0e-5 <= max_inlier_dist2 ) {
                                 inliers.add(other_match);
@@ -1707,28 +1708,28 @@ public class PanoramaProcessor {
         float y_scale = 1.0f;
 
         if( estimate_rotation && use_rotation ) {
-			/*if( true )
-				throw new RuntimeException(); // test*/
+            /*if( true )
+                throw new RuntimeException(); // test*/
 
             // first compute an ideal y_scale
-			/*if( estimate_y_scale && use_y_scale ) {
-				float y_scale_sum = 0.0f;
-				int n_y_scale = 0;
-				for(FeatureMatch match : actual_matches) {
-					float d0_y = points_arrays[0][match.index0].y - centres[0].y;
-					float d1_y = points_arrays[1][match.index1].y - centres[1].y;
-					if( Math.abs(d0_y) > min_rotation_dist && Math.abs(d1_y) > min_rotation_dist ) {
-						float this_y_scale = d1_y / d0_y;
-						y_scale_sum += this_y_scale;
-						n_y_scale++;
-						if( MyDebug.LOG )
-							Log.d(TAG, "    match has scale: " + this_y_scale);
-					}
-				}
-				if( n_y_scale > 0 ) {
-					y_scale = y_scale_sum / n_y_scale;
-				}
-			}*/
+            /*if( estimate_y_scale && use_y_scale ) {
+                float y_scale_sum = 0.0f;
+                int n_y_scale = 0;
+                for(FeatureMatch match : actual_matches) {
+                    float d0_y = points_arrays[0][match.index0].y - centres[0].y;
+                    float d1_y = points_arrays[1][match.index1].y - centres[1].y;
+                    if( Math.abs(d0_y) > min_rotation_dist && Math.abs(d1_y) > min_rotation_dist ) {
+                        float this_y_scale = d1_y / d0_y;
+                        y_scale_sum += this_y_scale;
+                        n_y_scale++;
+                        if( MyDebug.LOG )
+                            Log.d(TAG, "    match has scale: " + this_y_scale);
+                    }
+                }
+                if( n_y_scale > 0 ) {
+                    y_scale = y_scale_sum / n_y_scale;
+                }
+            }*/
 
             // compute an ideal rotation for a transformation where we rotate about centres[0], and then translate
             float angle_sum = 0.0f;
@@ -1826,10 +1827,10 @@ public class PanoramaProcessor {
                 Log.d(TAG, "        distance: " + match.distance);
             }
         }
-		/*if( Math.abs(rotation) > 30.0f*Math.PI/180.0f ) {
-			// test
-			throw new RuntimeException();
-		}*/
+        /*if( Math.abs(rotation) > 30.0f*Math.PI/180.0f ) {
+            // test
+            throw new RuntimeException();
+        }*/
 
         if( false && MyDebug.LOG ) {
             // debug:
@@ -1848,21 +1849,21 @@ public class PanoramaProcessor {
                     int off_x = (i==0) ? 0 : width;
                     boolean was_matched;
                     if( i == 0 ) {
-						/*if( MyDebug.LOG )
-							Log.d(TAG, "### has_matched0[" + j + "]: " + has_matched0[j]);*/
+                        /*if( MyDebug.LOG )
+                            Log.d(TAG, "### has_matched0[" + j + "]: " + has_matched0[j]);*/
                         was_matched = has_matched0[j];
                     }
                     else {
-						/*if( MyDebug.LOG )
-							Log.d(TAG, "### has_matched1[" + j + "]: " + has_matched1[j]);*/
+                        /*if( MyDebug.LOG )
+                            Log.d(TAG, "### has_matched1[" + j + "]: " + has_matched1[j]);*/
                         was_matched = has_matched1[j];
                     }
-					/*if( !was_matched ) {
-						continue;
-					}*/
-					if( i == 0 && rejected0[j] )
+                    /*if( !was_matched ) {
+                        continue;
+                    }*/
+                    if( i == 0 && rejected0[j] )
                         p.setColor(Color.CYAN);
-					else
+                    else
                         p.setColor(was_matched ? Color.YELLOW : Color.RED);
                     //canvas.drawCircle(points_arrays[i][j].x + off_x, points_arrays[i][j].y, 5.0f, p);
                     canvas.drawRect(points_arrays[i][j].x + off_x - feature_descriptor_radius - 1, points_arrays[i][j].y - feature_descriptor_radius - 1, points_arrays[i][j].x + off_x + feature_descriptor_radius + 1, points_arrays[i][j].y + feature_descriptor_radius + 1, p);
@@ -1929,9 +1930,9 @@ public class PanoramaProcessor {
                 for(int j=0;j<n_y;j++) {
                     int cy = (height*(j+1))/(n_y+1);
                     for(int k=0;k<2;k++) {
-						/*int off_x = (k==0) ? 0 : width + offset_x;
-						int off_y = (k==0) ? 0 : offset_y;
-						canvas.drawCircle(cx + off_x, cy + off_y, 5.0f, p);*/
+                        /*int off_x = (k==0) ? 0 : width + offset_x;
+                        int off_y = (k==0) ? 0 : offset_y;
+                        canvas.drawCircle(cx + off_x, cy + off_y, 5.0f, p);*/
                         int t_cx = cx, t_cy = cy;
                         if( k == 1 ) {
                             // transform
@@ -3134,7 +3135,7 @@ public class PanoramaProcessor {
             Allocation allocation = Allocation.createFromBitmap(rs, panorama);
             if( MyDebug.LOG )
                 Log.d(TAG, "### time after creating allocation_out: " + (System.currentTimeMillis() - time_s));
-            hdrProcessor.adjustHistogram(allocation, allocation, panorama.getWidth(), panorama.getHeight(), 0.25f, 1, true, time_s);
+            hdrProcessor.adjustHistogramRS(allocation, allocation, panorama.getWidth(), panorama.getHeight(), 0.25f, 1, true, time_s);
             if( MyDebug.LOG )
                 Log.d(TAG, "### time after adjustHistogram: " + (System.currentTimeMillis() - time_s));
             allocation.copyTo(panorama);
diff --git a/app/src/main/java/net/sourceforge/opencamera/StorageUtils.java b/app/src/main/java/net/sourceforge/opencamera/StorageUtils.java
index f9b51c915a09262c2fbb7a4d88b1a6410cc9b71d..9332ea28cd84fb2c0d4cc2c2f623ea557fe3e42c 100644
--- a/app/src/main/java/net/sourceforge/opencamera/StorageUtils.java
+++ b/app/src/main/java/net/sourceforge/opencamera/StorageUtils.java
@@ -809,6 +809,13 @@ public class StorageUtils {
             e.printStackTrace();
             throw new IOException();
         }
+        catch(NullPointerException e) {
+            // Have reports of this from Google Play for DocumentsContract.createDocument - better to fail gracefully and tell user rather than crash!
+            if( MyDebug.LOG )
+                Log.e(TAG, "createOutputMediaFileSAF failed with NullPointerException");
+            e.printStackTrace();
+            throw new IOException();
+        }
         catch(SecurityException e) {
             // Have reports of this from Google Play - better to fail gracefully and tell user rather than crash!
             if( MyDebug.LOG )
@@ -936,6 +943,23 @@ public class StorageUtils {
         return filename_without_ext;
     }
 
+    /** If the filename is for a "special" type HDR, NR or PANO, then return the filename with the
+     *  part of the filename e.g. "_HDR" onwards; else return null.
+     *  Received filename should not include an extension.
+     */
+    private static String filenameIsSpecial(String filename_without_ext) {
+        if( filename_without_ext.endsWith(ImageSaver.hdr_suffix) ) {
+            return filename_without_ext.substring(0, filename_without_ext.length()-ImageSaver.hdr_suffix.length());
+        }
+        if( filename_without_ext.endsWith(ImageSaver.nr_suffix) ) {
+            return filename_without_ext.substring(0, filename_without_ext.length()-ImageSaver.nr_suffix.length());
+        }
+        if( filename_without_ext.endsWith(ImageSaver.pano_suffix) ) {
+            return filename_without_ext.substring(0, filename_without_ext.length()-ImageSaver.pano_suffix.length());
+        }
+        return null;
+    }
+
     private enum UriType {
         MEDIASTORE_IMAGES,
         MEDIASTORE_VIDEOS
@@ -1123,6 +1147,79 @@ public class StorageUtils {
                             cursor.moveToPosition(dng_pos);
                         }
                     }
+                    else if( filename != null ) {
+                        // in cases where a HDR/NR/PANO photo was saved with base images, we should prefer the HDR image
+                        String filename_without_ext = filenameWithoutExtension(filename).toUpperCase(Locale.US);
+                        if( MyDebug.LOG )
+                            Log.d(TAG, "filename_without_ext: " + filename_without_ext);
+                        String filename_special_base = filenameIsSpecial(filename_without_ext);
+                        if( MyDebug.LOG )
+                            Log.d(TAG, "filename_special_base: " + filename_special_base);
+                        if( filename_special_base == null ) {
+                            String filename_base = null;
+                            // assume that base saved images are at most _XX
+                            if( filename_without_ext.length() >= 3 && filename_without_ext.charAt(filename_without_ext.length()-2) == '_' ) {
+                                filename_base = filename_without_ext.substring(0, filename_without_ext.length()-2);
+                            }
+                            else if( filename_without_ext.length() >= 4 && filename_without_ext.charAt(filename_without_ext.length()-3) == '_' ) {
+                                filename_base = filename_without_ext.substring(0, filename_without_ext.length()-3);
+                            }
+                            if( MyDebug.LOG )
+                                Log.d(TAG, "filename_base: " + filename_base);
+                            if( filename_base != null ) {
+                                int last_pos = cursor.getPosition();
+                                boolean found_special = false;
+                                int scan_count = 0;
+                                while( cursor.moveToNext() ) {
+                                    String next_filename = cursor.getString(column_name_c);
+                                    if( MyDebug.LOG )
+                                        Log.d(TAG, "next_filename: " + next_filename);
+                                    if( next_filename == null ) {
+                                        if( MyDebug.LOG )
+                                            Log.d(TAG, "done scanning, couldn't find filename");
+                                        break;
+                                    }
+                                    String next_filename_without_ext = filenameWithoutExtension(next_filename).toUpperCase(Locale.US);
+                                    if( MyDebug.LOG )
+                                        Log.d(TAG, "next_filename_without_ext: " + next_filename_without_ext);
+                                    String next_filename_special_base = filenameIsSpecial(next_filename_without_ext);
+                                    if( MyDebug.LOG )
+                                        Log.d(TAG, "next_filename_special_base: " + next_filename_special_base);
+                                    if( next_filename_special_base != null ) {
+                                        // found a special filename - is it the same base?
+                                        if( filename_base.equals(next_filename_special_base) ) {
+                                            // found a match
+                                            if( MyDebug.LOG )
+                                                Log.d(TAG, "found equivalent special");
+                                            found_special = true;
+                                            break;
+                                        }
+                                        else {
+                                            // found special, but doesn't match, so no point scanning further
+                                            if( MyDebug.LOG )
+                                                Log.d(TAG, "found another special");
+                                            break;
+                                        }
+                                    }
+                                    else if( !next_filename_without_ext.startsWith(filename_base) ) {
+                                        if( MyDebug.LOG )
+                                            Log.d(TAG, "no longer matches filename_base");
+                                        break;
+                                    }
+                                    else if( scan_count++ > 10 ) {
+                                        if( MyDebug.LOG )
+                                            Log.d(TAG, "give up scanning");
+                                        break;
+                                    }
+                                }
+                                if( !found_special ) {
+                                    if( MyDebug.LOG )
+                                        Log.d(TAG, "can't find equivalent non-special");
+                                    cursor.moveToPosition(last_pos);
+                                }
+                            }
+                        }
+                    }
                 }
 
                 long id = cursor.getLong(column_id_c);
diff --git a/app/src/main/java/net/sourceforge/opencamera/cameracontroller/CameraController.java b/app/src/main/java/net/sourceforge/opencamera/cameracontroller/CameraController.java
index a8404225e04eaf0b043b051accbe4873f63f3cfe..6ae4242ccb5d76ba3f28baa6aed529ab9c4c7c73 100644
--- a/app/src/main/java/net/sourceforge/opencamera/cameracontroller/CameraController.java
+++ b/app/src/main/java/net/sourceforge/opencamera/cameracontroller/CameraController.java
@@ -67,6 +67,7 @@ public abstract class CameraController {
         public List<CameraController.Size> video_sizes_high_speed; // may be null if high speed not supported
         public List<CameraController.Size> preview_sizes;
         public List<Integer> supported_extensions; // if non-null, list of supported camera vendor extensions, see https://developer.android.com/reference/android/hardware/camera2/CameraExtensionCharacteristics
+        public List<Integer> supported_extensions_zoom; // if non-null, list of camera vendor extensions that support zoom
         public List<String> supported_flash_values;
         public List<String> supported_focus_values;
         public float [] apertures; // may be null if not supported, else will have at least 2 values
@@ -354,6 +355,8 @@ public abstract class CameraController {
      *  Otherwise there is a risk when opening the camera that the textureview still shows an image from when
      *  the camera was previously opened (e.g., from pausing and resuming the application). This returns false (for CameraController2)
      *  when the camera has received its first frame.
+     *  Update: on more recent Android versions this didn't work very well, possibly due to a screenshot being used for "recent apps"
+     *  view; on Android 13+, the activity can make use of shouldCoverPreview(false) for this.
      */
     public boolean shouldCoverPreview() {
         return false;
diff --git a/app/src/main/java/net/sourceforge/opencamera/cameracontroller/CameraController1.java b/app/src/main/java/net/sourceforge/opencamera/cameracontroller/CameraController1.java
index 1601649ba7e98f3e201b7520103a2fd64f7af3a9..c5f0ca4a43d61188aba235b2bcf9b29dbf378a96 100644
--- a/app/src/main/java/net/sourceforge/opencamera/cameracontroller/CameraController1.java
+++ b/app/src/main/java/net/sourceforge/opencamera/cameracontroller/CameraController1.java
@@ -1628,17 +1628,36 @@ public class CameraController1 extends CameraController {
     public void autoFocus(final CameraController.AutoFocusCallback cb, boolean capture_follows_autofocus_hint) {
         if( MyDebug.LOG )
             Log.d(TAG, "autoFocus");
-        Camera.AutoFocusCallback camera_cb = new Camera.AutoFocusCallback() {
+        class MyAutoFocusCallback implements Camera.AutoFocusCallback {
             boolean done_autofocus = false;
+            private final Handler handler = new Handler();
+            private final Runnable runnable = new Runnable() {
+                @Override
+                public void run() {
+                    if( MyDebug.LOG )
+                        Log.d(TAG, "autofocus timeout check");
+                    if( !done_autofocus ) {
+                        Log.e(TAG, "autofocus timeout!");
+                        done_autofocus = true;
+                        cb.onAutoFocus(false);
+                    }
+                }
+            };
+
+            private void setTimeout() {
+                handler.postDelayed(runnable, 2000); // set autofocus timeout
+            }
 
             @Override
             public void onAutoFocus(boolean success, Camera camera) {
                 if( MyDebug.LOG )
                     Log.d(TAG, "autoFocus.onAutoFocus");
+                handler.removeCallbacks(runnable);
                 // in theory we should only ever get one call to onAutoFocus(), but some Samsung phones at least can call the callback multiple times
                 // see http://stackoverflow.com/questions/36316195/take-picture-fails-on-samsung-phones
                 // needed to fix problem on Samsung S7 with flash auto/on and continuous picture focus where it would claim failed to take picture even though it'd succeeded,
                 // because we repeatedly call takePicture(), and the subsequent ones cause a runtime exception
+                // update: also the done_autofocus flag is needed in case we had an autofocus timeout, see above
                 if( !done_autofocus ) {
                     done_autofocus = true;
                     cb.onAutoFocus(success);
@@ -1648,8 +1667,11 @@ public class CameraController1 extends CameraController {
                         Log.e(TAG, "ignore repeated autofocus");
                 }
             }
-        };
+        }
+        MyAutoFocusCallback camera_cb = new MyAutoFocusCallback();
+
         try {
+            camera_cb.setTimeout();
             camera.autoFocus(camera_cb);
         }
         catch(RuntimeException e) {
diff --git a/app/src/main/java/net/sourceforge/opencamera/cameracontroller/CameraController2.java b/app/src/main/java/net/sourceforge/opencamera/cameracontroller/CameraController2.java
index 92648b9d0cfa3b10ecd280a709d8422a05404c2c..b71a01f890951b43aba181ea64bc93d7da144f6b 100644
--- a/app/src/main/java/net/sourceforge/opencamera/cameracontroller/CameraController2.java
+++ b/app/src/main/java/net/sourceforge/opencamera/cameracontroller/CameraController2.java
@@ -64,6 +64,7 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.Locale;
 import java.util.Queue;
+import java.util.Set;
 import java.util.concurrent.Executor;
 
 import foundation.e.camera.R;
@@ -93,6 +94,7 @@ public class CameraController2 extends CameraController {
     private List<Integer> zoom_ratios;
     private int current_zoom_value;
     private int zoom_value_1x; // index into zoom_ratios list that is for zoom 1x
+    private List<Integer> supported_extensions_zoom; // if non-null, list of camera vendor extensions that support zoom
     private boolean supports_face_detect_mode_simple;
     private boolean supports_face_detect_mode_full;
     private boolean supports_optical_stabilization;
@@ -844,10 +846,7 @@ public class CameraController2 extends CameraController {
         }
 
         private void setControlZoomRatio(CaptureRequest.Builder builder) {
-            if( sessionType == SessionType.SESSIONTYPE_EXTENSION ) {
-                // don't set for extensions
-            }
-            else if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.R && has_control_zoom_ratio ) {
+            if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.R && has_control_zoom_ratio ) {
                 builder.set(CaptureRequest.CONTROL_ZOOM_RATIO, control_zoom_ratio);
             }
         }
@@ -1971,7 +1970,16 @@ public class CameraController2 extends CameraController {
             // need to communicate the problem to the application
             // n.b., as this is potentially serious error, we always log even if MyDebug.LOG is false
             Log.e(TAG, "error occurred after camera was opened");
-            camera_error_cb.onError();
+            // important to run on UI thread to avoid synchronisation issues in the Preview
+            final Activity activity = (Activity)context;
+            activity.runOnUiThread(new Runnable() {
+                @Override
+                public void run() {
+                    if( MyDebug.LOG )
+                        Log.d(TAG, "onError: call camera_error_cb.onError() on UI thread");
+                    camera_error_cb.onError();
+                }
+            });
         }
     }
 
@@ -2094,7 +2102,7 @@ public class CameraController2 extends CameraController {
                             Log.d(TAG, "callback done, about to notify");
                         open_camera_lock.notifyAll();
                         if( MyDebug.LOG )
-                            Log.d(TAG, "callback done, notification done");
+                            Log.d(TAG, "callback done, notify done");
                     }
                 }
             }
@@ -2131,7 +2139,7 @@ public class CameraController2 extends CameraController {
                             Log.d(TAG, "callback done, about to notify");
                         open_camera_lock.notifyAll();
                         if( MyDebug.LOG )
-                            Log.d(TAG, "callback done, notification done");
+                            Log.d(TAG, "callback done, notify done");
                     }
                 }
             }
@@ -2157,7 +2165,7 @@ public class CameraController2 extends CameraController {
                         Log.d(TAG, "callback done, about to notify");
                     open_camera_lock.notifyAll();
                     if( MyDebug.LOG )
-                        Log.d(TAG, "callback done, notification done");
+                        Log.d(TAG, "callback done, notify done");
                 }
             }
         }
@@ -2271,8 +2279,7 @@ public class CameraController2 extends CameraController {
             Log.d(TAG, "camera now opened: " + camera);
 
         /*{
-            // test error handling
-            final Handler handler = new Handler();
+            // test error handling on background thread
             handler.postDelayed(new Runnable() {
                 @Override
                 public void run() {
@@ -3003,6 +3010,7 @@ public class CameraController2 extends CameraController {
             List<Integer> extensions = extension_characteristics.getSupportedExtensions();
             if( extensions != null ) {
                 camera_features.supported_extensions = new ArrayList<>();
+                camera_features.supported_extensions_zoom = new ArrayList<>();
                 for(int extension : extensions) {
                     if( MyDebug.LOG )
                         Log.d(TAG, "vendor extension: " + extension);
@@ -3057,10 +3065,28 @@ public class CameraController2 extends CameraController {
                         if( MyDebug.LOG )
                             Log.d(TAG, "    extension is supported: " + extension);
                         camera_features.supported_extensions.add(extension);
+
+                        if( Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU ) {
+                            Set<CaptureRequest.Key> extension_supported_request_keys = extension_characteristics.getAvailableCaptureRequestKeys(extension);
+                            for(CaptureRequest.Key<?> key : extension_supported_request_keys) {
+                                if( MyDebug.LOG )
+                                    Log.d(TAG, "    supported capture request key: " + key.getName());
+                                if( key == CaptureRequest.CONTROL_ZOOM_RATIO ) {
+                                    camera_features.supported_extensions_zoom.add(extension);
+                                }
+                            }
+                            Set<CaptureResult.Key> extension_supported_result_keys = extension_characteristics.getAvailableCaptureResultKeys(extension);
+                            for(CaptureResult.Key<?> key : extension_supported_result_keys) {
+                                if( MyDebug.LOG )
+                                    Log.d(TAG, "    supported capture result key: " + key.getName());
+                            }
+                        }
                     }
                 }
             }
         }
+        // save to local fields:
+        this.supported_extensions_zoom = camera_features.supported_extensions_zoom;
 
         if( characteristics.get(CameraCharacteristics.FLASH_INFO_AVAILABLE) ) {
             int [] supported_flash_modes_arr = characteristics.get(CameraCharacteristics.CONTROL_AE_AVAILABLE_MODES); // Android format
@@ -4754,6 +4780,16 @@ public class CameraController2 extends CameraController {
                 Log.d(TAG, "zoom not supported");
             return;
         }
+        if( sessionType == SessionType.SESSIONTYPE_EXTENSION ) {
+            if( this.supported_extensions_zoom != null && this.supported_extensions_zoom.contains(camera_extension) ) {
+                // fine, camera extension supports zoom
+            }
+            else {
+                if( MyDebug.LOG )
+                    Log.d(TAG, "zoom not supported for camera extension");
+                return;
+            }
+        }
         if( value < 0 || value > zoom_ratios.size() ) {
             if( MyDebug.LOG )
                 Log.e(TAG, "invalid zoom value" + value);
@@ -7904,7 +7940,10 @@ public class CameraController2 extends CameraController {
 
             // for previewCaptureCallback, we set has_received_frame in onCaptureCompleted(), but
             // that method doesn't exist for ExtensionCaptureCallback, and the other methods such as
-            // onCaptureSequenceCompleted aren't called for the preview captures
+            // onCaptureSequenceCompleted aren't called for the preview captures;
+            // onCaptureResultAvailable meanwhile is only called if
+            // CameraExtensionCharacteristics.getAvailableCaptureResultKeys() returns a non-empty
+            // list
             if( !has_received_frame ) {
                 has_received_frame = true;
                 if( MyDebug.LOG )
@@ -7957,6 +7996,11 @@ public class CameraController2 extends CameraController {
             }
             super.onCaptureSequenceAborted(session, sequenceId);
         }
+
+        @Override
+        public void onCaptureResultAvailable(@NonNull CameraExtensionSession session, @NonNull CaptureRequest request, @NonNull TotalCaptureResult result) {
+            previewCaptureCallback.updateCachedCaptureResult(result);
+        }
     }
 
     private final MyCaptureCallback previewCaptureCallback = new MyCaptureCallback();
diff --git a/app/src/main/java/net/sourceforge/opencamera/preview/ApplicationInterface.java b/app/src/main/java/net/sourceforge/opencamera/preview/ApplicationInterface.java
index 5471f1df3f9ef97bdc8615ddba6d35290e9e303a..50115a24e6e0aa3f2edaba1e6a62621d811b3bbe 100644
--- a/app/src/main/java/net/sourceforge/opencamera/preview/ApplicationInterface.java
+++ b/app/src/main/java/net/sourceforge/opencamera/preview/ApplicationInterface.java
@@ -143,7 +143,18 @@ public interface ApplicationInterface {
     double getCalibratedLevelAngle(); // set to non-zero to calibrate the accelerometer used for the level angles
     boolean canTakeNewPhoto(); // whether taking new photos is allowed (e.g., can return false if queue for processing images would become full)
     boolean imageQueueWouldBlock(int n_raw, int n_jpegs); // called during some burst operations, whether we can allow taking the supplied number of extra photos
-    int getDisplayRotation(); // same behaviour as Activity.getWindowManager().getDefaultDisplay().getRotation() (including returning a member of Surface.ROTATION_*), but allows application to modify e.g. for upside-down preview
+    /** Same behaviour as Activity.getWindowManager().getDefaultDisplay().getRotation() (including
+     *  returning a member of Surface.ROTATION_*), but allows application to modify e.g. for
+     *  upside-down preview.
+     * @param prefer_later When the device orientation changes, there can be some ambiguity if this
+     *                     is called during this rotation, since getRotation() may updated shortly
+     *                     before the UI appears to rotate. If prefer_later==false, then prefer the
+     *                     previous rotation in such cases. This can be implemented by caching the
+     *                     value. prefer_later should be set to false when this is being called
+     *                     frequently e.g. as part of a UI that should smoothly rotate as the device
+     *                     rotates. prefer_later should be set to true for "one-off" calls.
+     */
+    int getDisplayRotation(boolean prefer_later);
     // Camera2 only modes:
     long getExposureTimePref(); // only called if getISOPref() is not "default"
     float getFocusDistancePref(boolean is_target_distance);
diff --git a/app/src/main/java/net/sourceforge/opencamera/preview/BasicApplicationInterface.java b/app/src/main/java/net/sourceforge/opencamera/preview/BasicApplicationInterface.java
index 32a97db8444be3a107b48be05c7c61466ada231d..bb577b2be437023cdd48687f5ee233c955dfb8b5 100644
--- a/app/src/main/java/net/sourceforge/opencamera/preview/BasicApplicationInterface.java
+++ b/app/src/main/java/net/sourceforge/opencamera/preview/BasicApplicationInterface.java
@@ -288,7 +288,7 @@ public abstract class BasicApplicationInterface implements ApplicationInterface
     }
 
     @Override
-    public int getDisplayRotation() {
+    public int getDisplayRotation(boolean prefer_later) {
         Activity activity = (Activity)this.getContext();
         return activity.getWindowManager().getDefaultDisplay().getRotation();
     }
diff --git a/app/src/main/java/net/sourceforge/opencamera/preview/Preview.java b/app/src/main/java/net/sourceforge/opencamera/preview/Preview.java
index 4e4fe633ea542c9b307a2967404c9eb1daf676d1..eb4e623b32030d2400f440687c12aee21d6e8cb7 100644
--- a/app/src/main/java/net/sourceforge/opencamera/preview/Preview.java
+++ b/app/src/main/java/net/sourceforge/opencamera/preview/Preview.java
@@ -336,6 +336,7 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
     private int current_size_index = -1; // this is an index into the sizes array, or -1 if sizes not yet set
 
     public List<Integer> supported_extensions; // if non-null, list of supported camera vendor extensions, see https://developer.android.com/reference/android/hardware/camera2/CameraExtensionCharacteristics
+    public List<Integer> supported_extensions_zoom; // if non-null, list of camera vendor extensions that support zoom
 
     private boolean supports_video;
     private boolean has_capture_rate_factor; // whether we have a capture rate for faster (timelapse) or slow motion
@@ -534,7 +535,7 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
             // for CameraController2, except testing on Nexus 6 shows that we shouldn't change "result" for front facing camera.
             boolean mirror = (camera_controller.getFacing() == CameraController.Facing.FACING_FRONT);
             camera_to_preview_matrix.setScale(1, mirror ? -1 : 1);
-            int degrees = getDisplayRotationDegrees();
+            int degrees = getDisplayRotationDegrees(false);
             int result = (camera_controller.getCameraOrientation() - degrees + 360) % 360;
             if( MyDebug.LOG ) {
                 Log.d(TAG, "orientation of display relative to natural orientation: " + degrees);
@@ -730,7 +731,7 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
         }
 
         // don't take a photo on touch if the user is touching to unpause!
-        if( !this.is_video && !was_paused && touch_capture ) {
+        if( !was_paused && touch_capture ) {
             if( MyDebug.LOG )
                 Log.d(TAG, "touch to capture");
             // Interpret as if user had clicked take photo/video button, except that we set the focus/metering areas.
@@ -763,15 +764,20 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
         private int multitouch_start_zoom_factor = 0;
 
         @Override
-        public boolean onScale(ScaleGestureDetector detector) {
-            if (Preview.this.camera_controller != null && Preview.this.has_zoom) {
-                Preview.this.scaleZoom(detector.getScaleFactor());
+        public boolean onScale(@NonNull ScaleGestureDetector detector) {
+            if( Preview.this.camera_controller != null && Preview.this.has_zoom ) {
+                float scale_factor = detector.getScaleFactor();
+                if( MyDebug.LOG )
+                    Log.d(TAG, "onScale: " + scale_factor);
+                // make pinch zoom more sensitive:
+                scale_factor = 1.0f + 2.0f*(scale_factor - 1.0f);
+                Preview.this.scaleZoom(scale_factor);
             }
             return true;
         }
 
         @Override
-        public boolean onScaleBegin(ScaleGestureDetector detector) {
+        public boolean onScaleBegin(@NonNull ScaleGestureDetector detector) {
             if( has_zoom && camera_controller != null ) {
                 has_multitouch_start_zoom_factor = true;
                 multitouch_start_zoom_factor = camera_controller.getZoom();
@@ -788,7 +794,7 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
         }
 
         @Override
-        public void onScaleEnd(ScaleGestureDetector detector) {
+        public void onScaleEnd(@NonNull ScaleGestureDetector detector) {
             if( MyDebug.LOG )
                 Log.d(TAG, "onScaleEnd");
             if( has_multitouch_start_zoom_factor && has_zoom && camera_controller != null && zoom_ratios.get(0) < 100 ) {
@@ -825,7 +831,7 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
     /** Returns whether we will take a photo on a double tap.
      */
     private boolean takePhotoOnDoubleTap() {
-        return !is_video && applicationInterface.getDoubleTapCapturePref();
+        return applicationInterface.getDoubleTapCapturePref();
     }
 
     @SuppressWarnings("SameReturnValue")
@@ -846,7 +852,7 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
 
     private class DoubleTapListener extends GestureDetector.SimpleOnGestureListener {
         @Override
-        public boolean onSingleTapConfirmed(MotionEvent e) {
+        public boolean onSingleTapConfirmed(@NonNull MotionEvent e) {
             if( MyDebug.LOG )
                 Log.d(TAG, "onSingleTapConfirmed");
             // If we're taking a photo on double tap, then for single taps we need to wait until these are confirmed
@@ -866,7 +872,7 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
         }
 
         @Override
-        public boolean onDoubleTap(MotionEvent e) {
+        public boolean onDoubleTap(@NonNull MotionEvent e) {
             if( MyDebug.LOG )
                 Log.d(TAG, "onDoubleTap");
             return Preview.this.onDoubleTap();
@@ -905,6 +911,10 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
 
         int previewWidth = MeasureSpec.getSize(widthSpec);
         int previewHeight = MeasureSpec.getSize(heightSpec);
+        if( MyDebug.LOG ) {
+            Log.d(TAG, "previewWidth: " + previewWidth);
+            Log.d(TAG, "previewHeight: " + previewHeight);
+        }
 
         // Get the padding of the border background.
         int hPadding = cameraSurface.getView().getPaddingLeft() + cameraSurface.getView().getPaddingRight();
@@ -914,20 +924,51 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
         previewWidth -= hPadding;
         previewHeight -= vPadding;
 
-        boolean widthLonger = previewWidth > previewHeight;
-        int longSide = (widthLonger ? previewWidth : previewHeight);
-        int shortSide = (widthLonger ? previewHeight : previewWidth);
-        if (longSide > shortSide * aspect_ratio) {
-            longSide = (int) ((double) shortSide * aspect_ratio);
-        } else {
-            shortSide = (int) ((double) longSide / aspect_ratio);
+        int result;
+        if( camera_controller != null ) {
+            // We shouldn't assume that previewWidth > previewHeight means the device is in landscape
+            // orientation - this isn't necessarily true for split-screen or multi-window mode.
+            // Important to use prefer_later==true, as in split-screen or multi-window mode, we don't always get a call
+            // to MainActivity.onConfigurationChanged() when device orientation changes, so have no way to know to
+            // reset the cached rotation. But we want the latest rotation value here anyway.
+            int degrees = getDisplayRotationDegrees(true);
+            result = (camera_controller.getCameraOrientation() - degrees + 360) % 360;
+            if( MyDebug.LOG ) {
+                Log.d(TAG, "orientation of display relative to natural orientation: " + degrees);
+                Log.d(TAG, "orientation of display relative to camera orientation: " + result);
+            }
         }
-        if (widthLonger) {
-            previewWidth = longSide;
-            previewHeight = shortSide;
-        } else {
-            previewWidth = shortSide;
-            previewHeight = longSide;
+        else {
+            // fall back to guessing via the window dimensions
+            result = (previewWidth > previewHeight) ? 0 : 90;
+        }
+        if( MyDebug.LOG )
+            Log.d(TAG, "aspect_ratio: " + aspect_ratio);
+        if( result % 180 != 0 ) {
+            // Usually this means the device is in portrait mode, and hence e.g. an aspect ratio of
+            // 4:3 should give an on-screen preview of 3:4 (since the device is rotated 90 degrees
+            // compared to the natural camera orientation).
+            // It's important to use this code instead of checking if the display is in portrait
+            // (or that previewWidth < previewHeight), for split-screen or multi-window displays.
+            // E.g., if the device orientation is in portrait, it might still be that Open Camera
+            // is running in landscape with previewWidth > previewHeight, because of running in
+            // split-screen mode, or more generally in multi-window mode where the window is resized
+            // to landscape orientation.
+            // See https://developer.android.com/training/camera2/camera-preview#relative_rotation .
+            aspect_ratio = 1.0f / aspect_ratio;
+            if( MyDebug.LOG )
+                Log.d(TAG, "aspect_ratio rotated to: " + aspect_ratio);
+        }
+
+        if( previewWidth > previewHeight * aspect_ratio ) {
+            previewWidth = (int) ((double) previewHeight * aspect_ratio);
+        }
+        else {
+            previewHeight = (int) ((double) previewWidth / aspect_ratio);
+        }
+        if( MyDebug.LOG ) {
+            Log.d(TAG, "previewWidth is now: " + previewWidth);
+            Log.d(TAG, "previewHeight is now: " + previewHeight);
         }
 
         // Add the padding of the border.
@@ -1064,9 +1105,16 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
                 Log.d(TAG, "nothing to do");
             return;
         }
-        if (MyDebug.LOG)
+        if( MyDebug.LOG ) {
             Log.d(TAG, "textureview size: " + textureview_w + ", " + textureview_h);
-        int rotation = applicationInterface.getDisplayRotation();
+            Log.d(TAG, "preview size: " + preview_w + ", " + preview_h);
+        }
+        // Important to use prefer_later==true, as in split-screen or multi-window mode, we don't always get a call
+        // to MainActivity.onConfigurationChanged() when device orientation changes, so have no way to know to
+        // reset the cached rotation. But we want the latest rotation value here anyway.
+        int rotation = applicationInterface.getDisplayRotation(true);
+        if( MyDebug.LOG )
+            Log.d(TAG, "configureTransform rotation: " + rotation);
         Matrix matrix = new Matrix();
         RectF viewRect = new RectF(0, 0, this.textureview_w, this.textureview_h);
         RectF bufferRect = new RectF(0, 0, this.preview_h, this.preview_w);
@@ -1754,7 +1802,9 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
                 public void onError() {
                     if (MyDebug.LOG)
                         Log.e(TAG, "error from CameraController: camera device failed");
-                    if (camera_controller != null) {
+                    if( camera_controller != null ) {
+                        if( MyDebug.LOG )
+                            Log.e(TAG, "set camera_controller to null");
                         camera_controller = null;
                         camera_open_state = CameraOpenState.CAMERAOPENSTATE_CLOSED;
                         applicationInterface.onCameraError();
@@ -2341,11 +2391,12 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
             this.video_quality_handler.setVideoSizesHighSpeed(camera_features.video_sizes_high_speed);
             this.supported_preview_sizes = camera_features.preview_sizes;
             this.supported_extensions = camera_features.supported_extensions;
+            this.supported_extensions_zoom = camera_features.supported_extensions_zoom;
 
             // need to do zoom last, as applicationInterface.allowZoom() may depend on the supported
-            // camera features (e.g., zoom not supported with camera extensions, so we need to have first
+            // camera features (e.g., zoom not necessarily supported with camera extensions, so we need to have first
             // stored supported_extensions - otherwise starting up in an extension photo mode will still
-            // show zoom controls)
+            // show zoom controls even if zoom not supported)
             this.camera_controller_supports_zoom = camera_features.is_zoom_supported;
             this.has_zoom = camera_features.is_zoom_supported && applicationInterface.allowZoom();
             if( this.has_zoom ) {
@@ -3797,12 +3848,14 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
             // (b) on some devices (e.g., Nokia 8), when coming back from the Settings when device is held in Preview,
             // display size is returned in portrait format! (To reproduce, enable "Maximise preview size"; or if that's
             // already enabled, change the setting off and on.)
-            if (display_size.x < display_size.y) {
+            if( MyDebug.LOG )
+                Log.d(TAG, "display_size: " + display_size.x + " x " + display_size.y);
+            if( display_size.x < display_size.y ) {
                 //noinspection SuspiciousNameCombination
                 display_size.set(display_size.y, display_size.x);
+                if( MyDebug.LOG )
+                    Log.d(TAG, "swapped display_size to: " + display_size.x + " x " + display_size.y);
             }
-            if (MyDebug.LOG)
-                Log.d(TAG, "display_size: " + display_size.x + " x " + display_size.y);
         }
         double targetRatio = calculateTargetRatioForPreview(display_size);
         int targetHeight = Math.min(display_size.y, display_size.x);
@@ -3932,28 +3985,18 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
 
     /** Returns the rotation in degrees of the display relative to the natural device orientation.
      */
-    private int getDisplayRotationDegrees() {
-        if (MyDebug.LOG)
-            Log.d(TAG, "getDisplayRotationDegrees");
-        int rotation = applicationInterface.getDisplayRotation();
+    private int getDisplayRotationDegrees(boolean prefer_later) {
+        int rotation = applicationInterface.getDisplayRotation(prefer_later);
         int degrees = 0;
         switch (rotation) {
-            case Surface.ROTATION_0:
-                degrees = 0;
-                break;
-            case Surface.ROTATION_90:
-                degrees = 90;
-                break;
-            case Surface.ROTATION_180:
-                degrees = 180;
-                break;
-            case Surface.ROTATION_270:
-                degrees = 270;
-                break;
+            case Surface.ROTATION_0: degrees = 0; break;
+            case Surface.ROTATION_90: degrees = 90; break;
+            case Surface.ROTATION_180: degrees = 180; break;
+            case Surface.ROTATION_270: degrees = 270; break;
             default:
                 break;
         }
-        if (MyDebug.LOG)
+        if( MyDebug.LOG )
             Log.d(TAG, "    degrees = " + degrees);
         return degrees;
     }
@@ -3967,12 +4010,13 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
                 Log.d(TAG, "camera not opened!");
             return;
         }
-        if (using_android_l) {
+        if( using_android_l ) {
             // need to configure the textureview
             configureTransform();
-        } else {
-            int degrees = getDisplayRotationDegrees();
-            if (MyDebug.LOG)
+        }
+        else {
+            int degrees = getDisplayRotationDegrees(true);
+            if( MyDebug.LOG )
                 Log.d(TAG, "    degrees = " + degrees);
             // note the code to make the rotation relative to the camera sensor is done in camera_controller.setDisplayOrientation()
             camera_controller.setDisplayOrientation(degrees);
@@ -4070,8 +4114,8 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
         } else {
             int cameraRotationOffset = camera_controller.getCameraOrientation();
             boolean isFrontFacing = camera_controller.getFacing() == CameraController.Facing.FACING_FRONT;
-            int rotation = isFrontFacing ? cameraRotationOffset + getDisplayRotationDegrees() :
-                    cameraRotationOffset - getDisplayRotationDegrees();
+            int rotation = isFrontFacing ? cameraRotationOffset + getDisplayRotationDegrees(true) :
+                    cameraRotationOffset - getDisplayRotationDegrees(true);
 
             current_rotation = (360 + rotation) % 360;
         }
@@ -4136,31 +4180,77 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
                 if( has_smooth_zoom )
                     smooth_zoom = zoom_ratios.get(max_zoom_factor)/100.0f;
             }
+            else if( has_smooth_zoom ) {
+                // Find the closest zoom level by rounding to nearest.
+                // Important to have same behaviour whether zooming in or out, otherwise problem when touching with two fingers and not
+                // moving - we'll get very small scale factors alternately between zooming in and out.
+                // The only reason we have separate codepath for zooming in or out is for performance (since we know to only look at
+                // higher or lower zoom ratios).
+                float dist = Math.abs(zoom_ratio - zoom_ratios.get(zoom_factor)/100.0f);
+                if( MyDebug.LOG )
+                    Log.d(TAG, "    current dist: " + dist);
+
+                if( scale_factor > 1.0f ) {
+                    // zooming in
+                    for(int i=zoom_factor+1;i<zoom_ratios.size();i++) {
+                        float this_dist = Math.abs(zoom_ratio - zoom_ratios.get(i)/100.0f);
+                        if( MyDebug.LOG )
+                            Log.d(TAG, "    this_dist: " + this_dist);
+                        if( this_dist < dist ) {
+                            new_zoom_factor = i;
+                            dist = this_dist;
+                            if( MyDebug.LOG )
+                                Log.d(TAG, "zoom in, found new zoom by comparing " + zoom_ratios.get(i)/100.0f + " to " + zoom_ratio + " , dist " + dist);
+                        }
+                        else if( this_dist > dist+1.0e-5f ) {
+                            break;
+                        }
+                    }
+                }
+                else {
+                    // zooming out
+                    for(int i=zoom_factor-1;i>=0;i--) {
+                        float this_dist = Math.abs(zoom_ratio - zoom_ratios.get(i)/100.0f);
+                        if( this_dist < dist ) {
+                            new_zoom_factor = i;
+                            dist = this_dist;
+                            if( MyDebug.LOG )
+                                Log.d(TAG, "zoom out, found new zoom by comparing " + zoom_ratios.get(i)/100.0f + " to " + zoom_ratio + " , dist " + dist);
+                        }
+                        else if( this_dist > dist+1.0e-5f ) {
+                            break;
+                        }
+                    }
+                }
+
+                smooth_zoom = zoom_ratio;
+            }
             else {
                 // find the closest zoom level
-                if (scale_factor > 1.0f) {
+                // unclear if we need this code anymore (smooth_zoom should always be true?)
+
+                if( scale_factor > 1.0f ) {
                     // zooming in
-                    for (int i = zoom_factor; i < zoom_ratios.size(); i++) {
-                        if (zoom_ratios.get(i) / 100.0f >= zoom_ratio) {
-                            if (MyDebug.LOG)
-                                Log.d(TAG, "zoom int, found new zoom by comparing " + zoom_ratios.get(i) / 100.0f + " >= " + zoom_ratio);
+                    for(int i=zoom_factor;i<zoom_ratios.size();i++) {
+                        if( zoom_ratios.get(i)/100.0f >= zoom_ratio ) {
+                            if( MyDebug.LOG )
+                                Log.d(TAG, "zoom in, found new zoom by comparing " + zoom_ratios.get(i)/100.0f + " >= " + zoom_ratio);
                             new_zoom_factor = i;
                             break;
                         }
                     }
-                } else {
+                }
+                else {
                     // zooming out
-                    for (int i = zoom_factor; i >= 0; i--) {
-                        if (zoom_ratios.get(i) / 100.0f <= zoom_ratio) {
-                            if (MyDebug.LOG)
-                                Log.d(TAG, "zoom out, found new zoom by comparing " + zoom_ratios.get(i) / 100.0f + " <= " + zoom_ratio);
+                    for(int i=zoom_factor;i>=0;i--) {
+                        if( zoom_ratios.get(i)/100.0f <= zoom_ratio ) {
+                            if( MyDebug.LOG )
+                                Log.d(TAG, "zoom out, found new zoom by comparing " + zoom_ratios.get(i)/100.0f + " <= " + zoom_ratio);
                             new_zoom_factor = i;
                             break;
                         }
                     }
                 }
-                if( has_smooth_zoom )
-                    smooth_zoom = zoom_ratio;
             }
             if (MyDebug.LOG) {
                 Log.d(TAG, "zoom_ratio is now " + zoom_ratio);
@@ -4615,8 +4705,12 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
     public void switchVideo(boolean during_startup, boolean change_user_pref) {
         if (MyDebug.LOG)
             Log.d(TAG, "switchVideo()");
-        if (camera_controller == null) {
-            if (MyDebug.LOG)
+        if( camera_controller == null && during_startup ) {
+            // if during_startup==false at least, we should allow switching to/from video mode if
+            // camera failed to open (it may be that the failure to open is specific to video mode
+            // for example, so should allow user to switch back to photo mode - e.g., setting
+            // video profile to sRGB on Pixel 6 Pro)
+            if( MyDebug.LOG )
                 Log.d(TAG, "camera not opened!");
             return;
         }
@@ -7204,6 +7298,12 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
         return this.supported_extensions != null && this.supported_extensions.contains(extension);
     }
 
+    /** Whether the camera vendor extensions supports zoom.
+     */
+    public boolean supportsZoomForCameraExtension(int extension) {
+        return this.supported_extensions_zoom != null && this.supported_extensions_zoom.contains(extension);
+    }
+
     public boolean supportsRaw() {
         return this.supports_raw;
     }
@@ -7674,14 +7774,20 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
             return;
         }
 
-        if (MyDebug.LOG)
+        if( MyDebug.LOG ) {
             Log.d(TAG, "showToast: " + message);
+            Log.d(TAG, "use_fake_toast: " + use_fake_toast);
+        }
 
-        if (this.app_is_paused) {
-            if (MyDebug.LOG)
-                Log.e(TAG, "don't show toast as application is paused: " + message);
-            // when targeting Android 11+, toasts with custom views won't be shown in background anyway - in theory we
-            // shouldn't be making toasts when in background, but check just in case
+        if( this.app_is_paused && use_fake_toast ) {
+            if( MyDebug.LOG )
+                Log.e(TAG, "don't show fake toast as application is paused: " + message);
+            // When targeting Android 11+, toasts with custom views won't be shown in background anyway - in theory we
+            // shouldn't be making toasts when in background, but check just in case.
+            // However we no longer use custom views when use_fake_toast==false, so fine to allow those - and indeed this
+            // is useful for cases where the toast is created shortly before Open Camera resumes, e.g., cancelling SAF
+            // (see toast in MainActivity.onActivityResult()), or denying location permission (see toast from
+            // PermissionHandler.onRequestPermissionsResult()).
             return;
         }
 
@@ -7691,9 +7797,9 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
         // Also for the use_fake_toast code, running the creation code, and the postDelayed code (and the code in clearActiveFakeToast()), on the UI thread avoids threading issues
         activity.runOnUiThread(new Runnable() {
             public void run() {
-                if (Preview.this.app_is_paused) {
-                    if (MyDebug.LOG)
-                        Log.e(TAG, "don't show toast as application is paused: " + message);
+                if( Preview.this.app_is_paused && use_fake_toast ) {
+                    if( MyDebug.LOG )
+                        Log.e(TAG, "don't show fake toast as application is paused: " + message);
                     // see note above
                     return;
                 }
@@ -7930,8 +8036,8 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
             final int downscale = 4;
             int bitmap_width = textureview_w / downscale;
             int bitmap_height = textureview_h / downscale;
-            int rotation = getDisplayRotationDegrees();
-            if (rotation == 90 || rotation == 270) {
+            int rotation = getDisplayRotationDegrees(false);
+            if( rotation == 90 || rotation == 270 ) {
                 int dummy = bitmap_width;
                 //noinspection SuspiciousNameCombination
                 bitmap_width = bitmap_height;
@@ -8295,7 +8401,7 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
                     // The original orientation of the bitmap we get from textureView.getBitmap() needs to be rotated to
                     // account for the orientation of camera vs device, but not to account for the current orientation
                     // of the device
-                    int rotation_degrees = preview.getDisplayRotationDegrees();
+                    int rotation_degrees = preview.getDisplayRotationDegrees(false);
 					/*if( MyDebug.LOG ) {
 						Log.d(TAG, "orientation of display relative to natural orientation: " + rotation_degrees);
 					}*/
@@ -8354,8 +8460,8 @@ public class Preview implements SurfaceHolder.Callback, TextureView.SurfaceTextu
                     output_allocation.destroy();
 
                     // See comments above for zebra stripes
-                    int rotation_degrees = preview.getDisplayRotationDegrees();
-                    if (MyDebug.LOG)
+                    int rotation_degrees = preview.getDisplayRotationDegrees(false);
+                    if( MyDebug.LOG )
                         Log.d(TAG, "time before creating new_focus_peaking_bitmap: " + (System.currentTimeMillis() - debug_time));
                     Matrix matrix = new Matrix();
                     matrix.postRotate(-rotation_degrees);
diff --git a/app/src/main/java/net/sourceforge/opencamera/ui/DrawPreview.java b/app/src/main/java/net/sourceforge/opencamera/ui/DrawPreview.java
index 42769763f549468abf10f31cbe50cdddc3d0b503..8c0cda5a2c71f23c9a2b904510e95a72aacf07b7 100644
--- a/app/src/main/java/net/sourceforge/opencamera/ui/DrawPreview.java
+++ b/app/src/main/java/net/sourceforge/opencamera/ui/DrawPreview.java
@@ -1579,7 +1579,7 @@ public class DrawPreview {
             }
         }
 
-        if( camera_controller != null ) {
+        if( camera_controller != null && !show_last_image ) {
             // draw histogram
             if( preview.isPreviewBitmapEnabled() ) {
                 int [] histogram = preview.getHistogram();
@@ -2212,7 +2212,7 @@ public class DrawPreview {
             int o_radius = (int) (10 * scale + 0.5f); // convert dps to pixels
             double angle = - preview.getOrigLevelAngle();
             // see http://android-developers.blogspot.co.uk/2010/09/one-screen-turn-deserves-another.html
-            int rotation = main_activity.getDisplayRotation();
+            int rotation = main_activity.getDisplayRotation(false);
             switch (rotation) {
                 case Surface.ROTATION_90:
                     angle -= 90.0;
@@ -2651,6 +2651,11 @@ public class DrawPreview {
     public void onDrawPreview(Canvas canvas) {
 		/*if( MyDebug.LOG )
 			Log.d(TAG, "onDrawPreview");*/
+		/*if( MyDebug.LOG )
+			Log.d(TAG, "onDrawPreview hardware accelerated: " + canvas.isHardwareAccelerated());*/
+
+        final long time_ms = System.currentTimeMillis();
+
         if( !has_settings ) {
             if( MyDebug.LOG )
                 Log.d(TAG, "onDrawPreview: need to update settings");
@@ -2660,8 +2665,6 @@ public class DrawPreview {
         CameraController camera_controller = preview.getCameraController();
         int ui_rotation = preview.getUIRotation();
 
-        final long time_ms = System.currentTimeMillis();
-
         // set up preview bitmaps (histogram etc)
         boolean want_preview_bitmap = want_histogram || want_zebra_stripes || want_focus_peaking;
         if( want_preview_bitmap != preview.isPreviewBitmapEnabled() ) {
@@ -2718,11 +2721,11 @@ public class DrawPreview {
                 float frac = ((time_now - camera_inactive_time_ms) / (float)dim_effect_time_c);
                 frac = Math.min(frac, 1.0f);
                 int alpha = (int)(frac * 127);
-                if( MyDebug.LOG ) {
+                /*if( MyDebug.LOG ) {
                     Log.d(TAG, "time diff: " + (time_now - camera_inactive_time_ms));
                     Log.d(TAG, "    frac: " + frac);
                     Log.d(TAG, "    alpha: " + alpha);
-                }
+                }*/
                 p.setColor(Color.BLACK);
                 p.setAlpha(alpha);
                 canvas.drawRect(0.0f, 0.0f, canvas.getWidth(), canvas.getHeight(), p);
@@ -2799,7 +2802,7 @@ public class DrawPreview {
             p.setAlpha(255);
         }
 
-        if( preview.isPreviewBitmapEnabled() ) {
+        if( preview.isPreviewBitmapEnabled() && !show_last_image ) {
             // draw additional real-time effects
 
             // draw zebra stripes
@@ -2925,6 +2928,11 @@ public class DrawPreview {
                 }
             }
         }
+
+        /*if( MyDebug.LOG ) {
+            long time_taken = System.currentTimeMillis() - time_ms;
+            Log.d(TAG, "onDrawPreview time: " + time_taken);
+        }*/
     }
 
     private void setLastImageMatrix(Canvas canvas, Bitmap bitmap, int this_ui_rotation, boolean flip_front) {
@@ -2973,6 +2981,14 @@ public class DrawPreview {
         float radius = (radius_dp * scale + 0.5f); // convert dps to pixels
         float cx = canvas.getWidth()/2.0f + distance_x;
         float cy = canvas.getHeight()/2.0f + distance_y;
+
+        // if gyro spots would be outside the field of view, it's still better to show them on the
+        // border of the canvas, so the user knows which direction to move the device
+        cx = Math.max(cx, 0.0f);
+        cx = Math.min(cx, canvas.getWidth());
+        cy = Math.max(cy, 0.0f);
+        cy = Math.min(cy, canvas.getHeight());
+
         canvas.drawCircle(cx, cy, radius, p);
         p.setAlpha(255);
         p.setStyle(Paint.Style.FILL); // reset
diff --git a/app/src/main/java/net/sourceforge/opencamera/ui/MainUI.java b/app/src/main/java/net/sourceforge/opencamera/ui/MainUI.java
index 72522aa5281dc3c1cdfe67f2b64aeaa0d4e95bc6..44fd83b21eda4699ef5e69dffd72f1a2cca5bfd3 100644
--- a/app/src/main/java/net/sourceforge/opencamera/ui/MainUI.java
+++ b/app/src/main/java/net/sourceforge/opencamera/ui/MainUI.java
@@ -202,6 +202,10 @@ public class MainUI {
         return UIPlacement.UIPLACEMENT_TOP;
     }
 
+    // stores with width and height of the last time we laid out the UI
+    public int layoutUI_display_w = -1;
+    public int layoutUI_display_h = -1;
+
     private void layoutUI(boolean popup_container_only) {
         long debug_time = 0;
         if (MyDebug.LOG) {
@@ -344,6 +348,12 @@ public class MainUI {
         Point display_size = new Point();
         Display display = main_activity.getWindowManager().getDefaultDisplay();
         display.getSize(display_size);
+        this.layoutUI_display_w = display_size.x;
+        this.layoutUI_display_h = display_size.y;
+        if( MyDebug.LOG ) {
+            Log.d(TAG, "layoutUI_display_w: " + layoutUI_display_w);
+            Log.d(TAG, "layoutUI_display_h: " + layoutUI_display_h);
+        }
         final int display_height = Math.min(display_size.x, display_size.y);
 
         final float scale = main_activity.getResources().getDisplayMetrics().density;
diff --git a/app/src/main/java/net/sourceforge/opencamera/ui/PopupView.java b/app/src/main/java/net/sourceforge/opencamera/ui/PopupView.java
index 7f55579d1991b1a9997842af81bd2dd4de0bac3f..8fb60804d2a68e02433a241f88bfa11ae0b0b710 100644
--- a/app/src/main/java/net/sourceforge/opencamera/ui/PopupView.java
+++ b/app/src/main/java/net/sourceforge/opencamera/ui/PopupView.java
@@ -349,7 +349,7 @@ public class PopupView extends LinearLayout {
                 // don't show auto-stabilise checkbox on popup if there's an on-screen icon
                 CheckBox checkBox = new CheckBox(main_activity);
                 checkBox.setText(getResources().getString(R.string.preference_auto_stabilise));
-                checkBox.setTextSize(TypedValue.COMPLEX_UNIT_DIP, standard_text_size_dip);
+                checkBox.setTextSize(TypedValue.COMPLEX_UNIT_SP, standard_text_size_dip);
                 checkBox.setTextColor(Color.WHITE);
                 {
                     // align the checkbox a bit better
@@ -1462,7 +1462,7 @@ public class PopupView extends LinearLayout {
                     ll2.addView(view);
 
                     button.setText(button_string);
-                    button.setTextSize(TypedValue.COMPLEX_UNIT_DIP, button_text_size_dip);
+                    button.setTextSize(TypedValue.COMPLEX_UNIT_SP, button_text_size_dip);
                     button.setTextColor(Color.WHITE);
                     // need 0 padding so we have enough room to display text for ISO buttons, when there are 6 ISO settings
                     final int padding = (int) (0 * scale + 0.5f); // convert dps to pixels
@@ -1564,7 +1564,7 @@ public class PopupView extends LinearLayout {
         final TextView text_view = view.findViewById(R.id.text_view);
 
         text_view.setText(title + ":");
-        text_view.setTextSize(TypedValue.COMPLEX_UNIT_DIP, title_text_size_dip);
+        text_view.setTextSize(TypedValue.COMPLEX_UNIT_SP, title_text_size_dip);
         text_view.setTypeface(null, Typeface.BOLD);
         text_view.setPadding(0, 5, 0, 5);
         //text_view.setBackgroundColor(Color.GRAY); // debug
@@ -1627,7 +1627,7 @@ public class PopupView extends LinearLayout {
 
             final TextView text_view = new TextView(this.getContext());
             text_view.setText(title);
-            text_view.setTextSize(TypedValue.COMPLEX_UNIT_DIP, standard_text_size_dip);
+            text_view.setTextSize(TypedValue.COMPLEX_UNIT_SP, standard_text_size_dip);
             text_view.setTextColor(Color.WHITE);
             text_view.setGravity(Gravity.CENTER);
             text_view.setSingleLine(true); // if text too long for the button, we'd rather not have wordwrap, even if it means cutting some text off
@@ -1757,7 +1757,7 @@ public class PopupView extends LinearLayout {
             button.setId(count);
 
             button.setText(supported_option_entry);
-            button.setTextSize(TypedValue.COMPLEX_UNIT_DIP, standard_text_size_dip);
+            button.setTextSize(TypedValue.COMPLEX_UNIT_SP, standard_text_size_dip);
             button.setTextColor(Color.WHITE);
             if( MyDebug.LOG )
                 Log.d(TAG, "addRadioOptionsToGroup time 3: " + (System.nanoTime() - debug_time));
@@ -1851,7 +1851,7 @@ public class PopupView extends LinearLayout {
 
             setArrayOptionsText(supported_options, title, text_view, title_in_options, title_in_options_first_only, current_index);
             //text_view.setBackgroundColor(Color.GRAY); // debug
-            text_view.setTextSize(TypedValue.COMPLEX_UNIT_DIP, standard_text_size_dip);
+            text_view.setTextSize(TypedValue.COMPLEX_UNIT_SP, standard_text_size_dip);
             text_view.setSingleLine(true); // if text too long for the button, we'd rather not have wordwrap, even if it means cutting some text off
             LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT, 1.0f);
             // Yuck! We want the arrow_button_w to be fairly large so that users can touch the arrow buttons easily, but if
diff --git a/app/src/main/res/values-pl/strings.xml b/app/src/main/res/values-pl/strings.xml
index 2373d67a29b355fed99ce9ee9b07194644cffb89..18f091e9d26e05ca36972f267744abe95efb17cf 100644
--- a/app/src/main/res/values-pl/strings.xml
+++ b/app/src/main/res/values-pl/strings.xml
@@ -961,4 +961,15 @@
     <string name="photo_mode_x_beauty">X-Bty</string> <!-- keep short, as this shows in the popup menu -->
     <string name="photo_mode_x_beauty_full">Rozszerzenie: Piękno / Retusz twarzy</string>
 
+    <string name="preference_hdr_tonemapping">Mapowanie tonalne HDR</string>
+    <string name="preference_hdr_tonemapping_summary">Algorytm używany do mapowania tonów w trybie zdjęć HDR\n%s</string>
+    <string name="preference_hdr_tonemapping_clamp">Prosty clamp</string>
+    <string name="preference_hdr_tonemapping_exponential">Wykładniczo</string>
+    <string name="preference_hdr_tonemapping_default">Domyślnie</string>
+
+    <string name="preference_remove_device_exif">Usuń dane EXIF urządzenia</string>
+    <string name="preference_remove_device_exif_summary">Czy usuwać metadane EXIF urządzenia ze zdjęć JPEG. Nie spowoduje to usunięcia znaczników exif zastosowanych w innych ustawieniach, które stosują metadane EXIF (np. lokalizacja/geotagowanie). Te inne opcje są niezależne i zastąpią to ustawienie. Nie dotyczy to zdjęć RAW/DNG oraz filmów.\n%s</string>
+    <string name="preference_remove_device_exif_off">Nie usuwaj danych EXIF urządzenia</string>
+    <string name="preference_remove_device_exif_on">Usuń dane EXIF urządzenia</string>
+    <string name="preference_remove_device_exif_keep_datetime">Usuń z wyjątkiem daty/godziny</string>
 </resources>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 2ab7f9bc1c91f0d7db42da7c5a16e26bcc579ea5..ec96043cd3e21ba901b4b6812642557e65fef1dd 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -100,7 +100,7 @@
     <string name="preference_burst_interval">Repeat mode interval</string>
     <string name="preference_screen_camera_controls_more">More camera controls…</string>
     <string name="preference_touch_capture">Touch to capture</string>
-    <string name="preference_touch_capture_summary">Take a photo just by touching or double-tapping the preview</string>
+    <string name="preference_touch_capture_summary">Take a photo or record video just by touching or double-tapping the preview</string>
     <string name="preference_pause_preview">Pause after taking photo</string>
     <string name="preference_pause_preview_summary">Pause the screen after taking a photo, with the option to share or delete the photo</string>
     <string name="preference_shutter_sound">Shutter sound</string>
@@ -1052,7 +1052,7 @@
 
     <string name="preference_screen_licences">Open Source licences</string>
     <string name="preference_licence_open_camera">Camera</string>
-    <string name="preference_licence_open_camera_text">Camera is © 2013–2019 Mark Harman, released under the GPL v3 or later. Tap here for full licence text.</string>
+    <string name="preference_licence_open_camera_text">Camera is © 2013–2023 Mark Harman, released under the GPL v3 or later. Tap here for full licence text.</string>
     <string name="preference_licence_google_icons">Google\'s Material Design icons</string>
     <string name="preference_licence_google_icons_text">Camera uses icons from Google\'s Material Design icons
         (https://developer.android.com/design/downloads/index.html ,
@@ -1067,17 +1067,16 @@
     <string name="whats_new_text" translatable="false">
         <small>[This dialog is shown when Camera is updated. You can disable it under
             Settings/On screen GUI/Show What\'s New dialog.]</small>
-        \n\n<b>v1.51:</b>\n
+        \n\n<b>v1.52:</b>\n
         <ul>
-            <li>New option Settings/Photo settings/\"Remove device EXIF data\" to remove device metadata from JPEG photos.\n</li>
-            <li>New option Settings/Photo settings/\"HDR tonemapping\" to choose tonemapping algorithm used for HDR photo mode.\n</li>
-            <li>Fixed slow focusing for Camera2 API on some devices.\n</li>
-            <li>Fixed incorrect thumbnail orientation on some devices.\n</li>
-            <li>Fixed focus bracketing on some devices.\n</li>
-            <li>Fixed geotagging not working on some devices.\n</li>
-            <li>Improvement to HDR algorithm for dark scenes.\n</li>
-            <li>Default to Camera2 API for some devices (will only take affect for new installs or if resetting settings).\n</li>
-            <li>Various other UI improvements and bug fixes.\n</li>
+            <li>Improvements for pinch zooming.\n</li>
+            <li>Fixes for split-screen and multi-window mode.\n</li>
+            <li>Support for zoom and on-screen ISO/exposure display when using camera vendor extensions (for supported Android 13+ devices).\n</li>
+            <li>\"Touch to capture\" option now supports starting and stopping video.\n</li>
+            <li>Applied a 2s timeout for focusing with original camera API.\n</li>
+            <li>Improved performance for NR photo mode.\n</li>
+            <li>No longer cancel panorama when rotating device too far in wrong direction.\n</li>
+            <li>Various other improvements and bug fixes.\n</li>
         </ul>
     </string>
 
diff --git a/app/src/main/rs/avg_brighten.rs b/app/src/main/rs/avg_brighten.rs
index 824d41df4684d016ce0ccd7f0813f9d16bf03d9b..04eaa659f9305c30b7635eadf6d865560de5e0da 100644
--- a/app/src/main/rs/avg_brighten.rs
+++ b/app/src/main/rs/avg_brighten.rs
@@ -151,11 +151,12 @@ uchar4 __attribute__((kernel)) avg_brighten_f(float3 rgb, uint32_t x, uint32_t y
         // if making canges to this (especially radius, C), run AvgTests - in particular, pay close
         // attention to:
         // testAvg6: don't want to make the postcard too blurry
-        // testAvg8: zoom in to 60%, ensure still appears reasonably sharp
+        // testAvg8: zoom in to 600%, ensure still appears reasonably sharp
         // testAvg23: ensure we do reduce the noise, e.g., view around "vicks", without making the
         // text blurry
         // testAvg24: want to reduce the colour noise near the wall, but don't blur out detail, e.g.
         // at the flowers
+        // testAvg31
         // Also need to be careful of performance.
         /*float old_value = fmax(rgb.r, rgb.g);
         old_value = fmax(old_value, rgb.b);*/
@@ -236,10 +237,12 @@ uchar4 __attribute__((kernel)) avg_brighten_f(float3 rgb, uint32_t x, uint32_t y
     {
         // spatial noise reduction filter, colour only
         // if changing this, see list of tests under standard spatial noise reduction above
-        float old_value = fmax(rgb.r, rgb.g);
-        old_value = fmax(old_value, rgb.b);
+        //float old_value = fmax(rgb.r, rgb.g);
+        //old_value = fmax(old_value, rgb.b);
+        float old_value = rgb.g; // use only green component for performance
         float3 sum = 0.0;
-        int radius = 3;
+        //int radius = 3;
+        int radius = 2;
         int count = 0;
         int sx = (x >= radius) ? x-radius : 0;
         int ex = (x < width-radius) ? x+radius : width-1;
@@ -251,14 +254,16 @@ uchar4 __attribute__((kernel)) avg_brighten_f(float3 rgb, uint32_t x, uint32_t y
                 {
                     float3 this_pixel = rsGetElementAt_float3(bitmap, cx, cy);
                     {
-                        float this_value = fmax(this_pixel.r, this_pixel.g);
-                        this_value = fmax(this_value, this_pixel.b);
+                        //float this_value = fmax(this_pixel.r, this_pixel.g);
+                        //this_value = fmax(this_value, this_pixel.b);
+                        float this_value = this_pixel.g; // use only green component for performance
                         if( this_value > 0.5f )
                             this_pixel *= old_value/this_value;
                         // use a wiener filter, so that more similar pixels have greater contribution
                         // smaller value of C means stronger filter (i.e., less averaging)
                         // for now set at same value as standard spatial filter above
-                        const float C = 64.0f*64.0f/8.0f;
+                        //const float C = 64.0f*64.0f/8.0f;
+                        const float C = 16.0f*16.0f/8.0f;
                         float3 diff = rgb - this_pixel;
                         float L = dot(diff, diff);
                         //L = 0.0f; // test no wiener filter
diff --git a/app/src/main/rs/process_avg.rs b/app/src/main/rs/process_avg.rs
index 38dd07798d6f72e0cba1a2887d8c0046a2a16400..2ece2d3b8ac52dc3563e9b455bddf3c665df512e 100644
--- a/app/src/main/rs/process_avg.rs
+++ b/app/src/main/rs/process_avg.rs
@@ -86,7 +86,7 @@ float3 __attribute__((kernel)) avg_f(float3 pixel_avg_f, uint32_t x, uint32_t y)
             L += dot(diff, diff);
             diff = convert_float3(rsGetElementAt_uchar4(bitmap_orig, ix-2, iy+2).rgb) - convert_float3(rsGetElementAt_uchar4(bitmap_new, ox-2, oy+2).rgb);
             L += dot(diff, diff);
-            diff = convert_float3(rsGetElementAt_uchar4(bitmap_orig, ix-2, iy+2).rgb) - convert_float3(rsGetElementAt_uchar4(bitmap_new, ox+2, oy+2).rgb);
+            diff = convert_float3(rsGetElementAt_uchar4(bitmap_orig, ix+2, iy+2).rgb) - convert_float3(rsGetElementAt_uchar4(bitmap_new, ox+2, oy+2).rgb);
             L += dot(diff, diff);
 
             L /= n_pixels;
diff --git a/app/src/main/rs/process_hdr.rs b/app/src/main/rs/process_hdr.rs
index ae3696c43a650f784168dd0051b156b20e02345b..877ce1ecb36e63461a67ea58f17e96ff5da168bd 100644
--- a/app/src/main/rs/process_hdr.rs
+++ b/app/src/main/rs/process_hdr.rs
@@ -43,13 +43,13 @@ const int tonemap_algorithm_aces_c = 4;
 
 int tonemap_algorithm = tonemap_algorithm_reinhard_c;
 
-// for Exponential:
+// for Exponential; should match setting in HDRProcessor.java:
 const float exposure = 1.2f;
 
 // for Reinhard:
 float tonemap_scale = 1.0f;
 
-// for FU2:
+// for FU2; should match setting in HDRProcessor.java:
 const float fu2_exposure_bias = 2.0f / 255.0f;
 float W = 11.2f;
 
@@ -520,7 +520,18 @@ uchar4 __attribute__((kernel)) hdr_n(uchar4 in, uint32_t x, uint32_t y) {
         float avg = (rgb.r+rgb.g+rgb.b) / 3.0f;
         float diff = fabs( avg - 127.5f );
         float weight = 1.0f;
-        if( diff > safe_range_c ) {
+        if( avg <= 127.5f ) {
+            // see comment for corresponding code in hdr()
+            const float range_low_c = 32.0f;
+            const float range_high_c = 48.0f;
+            if( avg <= range_low_c ) {
+                weight = 0.0f;
+            }
+            else if( avg <= range_high_c ) {
+                weight = (avg - range_low_c) / (range_high_c - range_low_c);
+            }
+        }
+        else if( diff > safe_range_c ) {
             // scaling chosen so that 0 and 255 map to a non-zero weight of 0.01
             weight = 1.0f - 0.99f * (diff - safe_range_c) / (127.5f - safe_range_c);
         }
@@ -569,6 +580,9 @@ uchar4 __attribute__((kernel)) hdr_n(uchar4 in, uint32_t x, uint32_t y) {
                 // there will be at least one more adjacent image to look at
                 avg = (rgb.r+rgb.g+rgb.b) / 3.0f;
                 diff = fabs( avg - 127.5f );
+
+                // n.b., we don't have the codepath here for "if( avg <= 127.5f )" - causes problems
+                // for testHDR_exp5 (black blotches)
                 if( diff > safe_range_c ) {
                     // scaling chosen so that 0 and 255 map to a non-zero weight of 0.01
                     weight *= 1.0f - 0.99f * (diff - safe_range_c) / (127.5f - safe_range_c);
diff --git a/gradle.properties b/gradle.properties
index 4ff57088dee773ca551b90a3cba6e158e8a8ffbd..5fc115c6b81d589d3cef2456e92348318b1943cb 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,4 +1,5 @@
 android.useAndroidX=true
+android.defaults.buildfeatures.buildconfig=true
 android.enableJetifier=true
 org.gradle.jvmargs=-Xmx1400m
 org.gradle.parallel=true
diff --git a/opencamera_source.txt b/opencamera_source.txt
index 65e866c972feac823ced9dda64fd9a86af747df3..7dd5fe32307691bcd1348bf9489c12a483cbb0c8 100644
--- a/opencamera_source.txt
+++ b/opencamera_source.txt
@@ -22,7 +22,7 @@ Application: You might prefer to use Open Camera in its entirety, as an Activity
 If you are using the Open Camera source code, there are some obvious things to change:
 * Package name
 * Online help / homepage (see MainActivity.getOnlineHelpUrl())
-* Privacy policy information, including name and email contact (see "preference_privacy_policy_text" in strings.xml)
+* Licence and privacy policy information, including name and email contact (see "preference_licence_open_camera_text" and "preference_privacy_policy_text" in strings.xml)
 
 Android inspection warnings/errors
 ==================================
@@ -57,4 +57,4 @@ Homepage: http://opencamera.org.uk/
 
 Google Play download: https://play.google.com/store/apps/details?id=net.sourceforge.opencamera
 
-Mark Harman 6 December 2022
+Mark Harman 18 February 2023