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Commit 8f612b45 authored by TreeHugger Robot's avatar TreeHugger Robot Committed by Android (Google) Code Review
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Merge "Camera: Improve documentation for android.control.zoomRatio" into rvc-dev

parents bb044fc8 878f9df9

camera/ndk/include/camera/NdkCameraMetadataTags.h

+61 −20
Original line number Diff line number Diff line
@@ -1895,27 +1895,66 @@ typedef enum acamera_metadata_tag { 
     * ACAMERA_SCALER_CROP_REGION can still be used to specify the horizontal or vertical

     * crop to achieve aspect ratios different than the native camera sensor.</p>

     * <p>By using this control, the application gains a simpler way to control zoom, which can

     * be a combination of optical and digital zoom. More specifically, for a logical

     * multi-camera with more than one focal length, using a floating point zoom ratio offers

     * more zoom precision when a telephoto lens is used, as well as allowing zoom ratio of

     * less than 1.0 to zoom out to a wide field of view.</p>

     * <p>Note that the coordinate system of cropRegion, AE/AWB/AF regions, and faces now changes

     * to the effective after-zoom field-of-view represented by rectangle of (0, 0,

     * activeArrayWidth, activeArrayHeight).</p>

     * <p>For example, if ACAMERA_SENSOR_INFO_ACTIVE_ARRAY_SIZE is 4032*3024, and the preview stream

     * is configured to the same 4:3 aspect ratio, the application can achieve 2.0x zoom in

     * one of two ways:</p>

     * <ul>

     * <li>zoomRatio = 2.0, scaler.cropRegion = (0, 0, 4032, 3024)</li>

     * <li>zoomRatio = 1.0 (default), scaler.cropRegion = (1008, 756, 3024, 2268)</li>

     * be a combination of optical and digital zoom. For example, a multi-camera system may

     * contain more than one lens with different focal lengths, and the user can use optical

     * zoom by switching between lenses. Using zoomRatio has benefits in the scenarios below:

     * <em> Zooming in from a wide-angle lens to a telephoto lens: A floating-point ratio provides

     *   better precision compared to an integer value of ACAMERA_SCALER_CROP_REGION.

     * </em> Zooming out from a wide lens to an ultrawide lens: zoomRatio supports zoom-out whereas

     *   ACAMERA_SCALER_CROP_REGION doesn't.</p>

     * <p>To illustrate, here are several scenarios of different zoom ratios, crop regions,

     * and output streams, for a hypothetical camera device with an active array of size

     * <code>(2000,1500)</code>.</p>

     * <ul>

     * <li>Camera Configuration:<ul>

     * <li>Active array size: <code>2000x1500</code> (3 MP, 4:3 aspect ratio)</li>

     * <li>Output stream #1: <code>640x480</code> (VGA, 4:3 aspect ratio)</li>

     * <li>Output stream #2: <code>1280x720</code> (720p, 16:9 aspect ratio)</li>

     * </ul>

     * </li>

     * <li>Case #1: 4:3 crop region with 2.0x zoom ratio<ul>

     * <li>Zoomed field of view: 1/4 of original field of view</li>

     * <li>Crop region: <code>Rect(0, 0, 2000, 1500) // (left, top, right, bottom)</code> (post zoom)</li>

     * </ul>

     * </li>

     * <li><img alt="4:3 aspect ratio crop diagram" src="../images/camera2/metadata/android.control.zoomRatio/zoom-ratio-2-crop-43.png" /><ul>

     * <li><code>640x480</code> stream source area: <code>(0, 0, 2000, 1500)</code> (equal to crop region)</li>

     * <li><code>1280x720</code> stream source area: <code>(0, 187, 2000, 1312)</code> (letterboxed)</li>

     * </ul>

     * <p>If the application intends to set aeRegions to be top-left quarter of the preview

     * field-of-view, the ACAMERA_CONTROL_AE_REGIONS should be set to (0, 0, 2016, 1512) with

     * </li>

     * <li>Case #2: 16:9 crop region with 2.0x zoom.<ul>

     * <li>Zoomed field of view: 1/4 of original field of view</li>

     * <li>Crop region: <code>Rect(0, 187, 2000, 1312)</code></li>

     * <li><img alt="16:9 aspect ratio crop diagram" src="../images/camera2/metadata/android.control.zoomRatio/zoom-ratio-2-crop-169.png" /></li>

     * <li><code>640x480</code> stream source area: <code>(250, 187, 1750, 1312)</code> (pillarboxed)</li>

     * <li><code>1280x720</code> stream source area: <code>(0, 187, 2000, 1312)</code> (equal to crop region)</li>

     * </ul>

     * </li>

     * <li>Case #3: 1:1 crop region with 0.5x zoom out to ultrawide lens.<ul>

     * <li>Zoomed field of view: 4x of original field of view (switched from wide lens to ultrawide lens)</li>

     * <li>Crop region: <code>Rect(250, 0, 1750, 1500)</code></li>

     * <li><img alt="1:1 aspect ratio crop diagram" src="../images/camera2/metadata/android.control.zoomRatio/zoom-ratio-0.5-crop-11.png" /></li>

     * <li><code>640x480</code> stream source area: <code>(250, 187, 1750, 1312)</code> (letterboxed)</li>

     * <li><code>1280x720</code> stream source area: <code>(250, 328, 1750, 1172)</code> (letterboxed)</li>

     * </ul>

     * </li>

     * </ul>

     * <p>As seen from the graphs above, the coordinate system of cropRegion now changes to the

     * effective after-zoom field-of-view, and is represented by the rectangle of (0, 0,

     * activeArrayWith, activeArrayHeight). The same applies to AE/AWB/AF regions, and faces.

     * This coordinate system change isn't applicable to RAW capture and its related

     * metadata such as intrinsicCalibration and lensShadingMap.</p>

     * <p>Using the same hypothetical example above, and assuming output stream #1 (640x480) is

     * the viewfinder stream, the application can achieve 2.0x zoom in one of two ways:</p>

     * <ul>

     * <li>zoomRatio = 2.0, scaler.cropRegion = (0, 0, 2000, 1500)</li>

     * <li>zoomRatio = 1.0 (default), scaler.cropRegion = (500, 375, 1500, 1125)</li>

     * </ul>

     * <p>If the application intends to set aeRegions to be top-left quarter of the viewfinder

     * field-of-view, the ACAMERA_CONTROL_AE_REGIONS should be set to (0, 0, 1000, 750) with

     * zoomRatio set to 2.0. Alternatively, the application can set aeRegions to the equivalent

     * region of (1008, 756, 2016, 1512) for zoomRatio of 1.0. If the application doesn't

     * region of (500, 375, 1000, 750) for zoomRatio of 1.0. If the application doesn't

     * explicitly set ACAMERA_CONTROL_ZOOM_RATIO, its value defaults to 1.0.</p>

     * <p>This coordinate system change isn't applicable to RAW capture and its related metadata

     * such as intrinsicCalibration and lensShadingMap.</p>

     * <p>One limitation of controlling zoom using zoomRatio is that the ACAMERA_SCALER_CROP_REGION

     * must only be used for letterboxing or pillarboxing of the sensor active array, and no

     * FREEFORM cropping can be used with ACAMERA_CONTROL_ZOOM_RATIO other than 1.0.</p>
@@ -1923,7 +1962,6 @@ typedef enum acamera_metadata_tag { 
     * @see ACAMERA_CONTROL_AE_REGIONS

     * @see ACAMERA_CONTROL_ZOOM_RATIO

     * @see ACAMERA_SCALER_CROP_REGION

     * @see ACAMERA_SENSOR_INFO_ACTIVE_ARRAY_SIZE

     */

    ACAMERA_CONTROL_ZOOM_RATIO =                                // float

            ACAMERA_CONTROL_START + 47,
@@ -2395,8 +2433,11 @@ typedef enum acamera_metadata_tag { 
     * frames before the lens can change to the requested focal length.

     * While the focal length is still changing, ACAMERA_LENS_STATE will

     * be set to MOVING.</p>

     * <p>Optical zoom will not be supported on most devices.</p>

     * <p>Optical zoom via this control will not be supported on most devices. Starting from API

     * level 30, the camera device may combine optical and digital zoom through the

     * ACAMERA_CONTROL_ZOOM_RATIO control.</p>

     *

     * @see ACAMERA_CONTROL_ZOOM_RATIO

     * @see ACAMERA_LENS_APERTURE

     * @see ACAMERA_LENS_FOCUS_DISTANCE

     * @see ACAMERA_LENS_STATE