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Commit 04c78a99 authored by Anthony Han's avatar Anthony Han
Browse files

Interpolate low light white balance 

Instead of setting color temperature to a default in low lux conditions,
add a spline to interpolate from color temperature that reflects the
ambient to a default.

Bug: 131259669
Test: atest AmbientLuxTest

Change-Id: I623190b796c67bab88e2eea3b4cf5a5b9ba14ae2
parent 9ad9609f

core/res/res/values/config.xml

+22 −3
Original line number Diff line number Diff line
@@ -4017,9 +4017,28 @@ 
    </array>



    <!-- See DisplayWhiteBalanceController.

         The ambient brightness threshold (in lux) beneath which we fall back to a fixed ambient

         color temperature. -->

    <item name="config_displayWhiteBalanceLowLightAmbientBrightnessThreshold" format="float" type="dimen">10.0</item>

         A float array containing a list of ambient brightnesses, in Lux. This array,

         together with config_displayWhiteBalanceLowLightAmbientBiases, is used to generate a

         lookup table used in DisplayWhiteBalanceController. This lookup table is used to map

         ambient brightness readings to a bias, where the bias is used to linearly interpolate

         between ambient color temperature and

         config_displayWhiteBalanceLowLightAmbientColorTemperature.

         This table is optional. If used, this array must,

         1) Contain at least two entries

         2) Be the same length as config_displayWhiteBalanceLowLightAmbientBiases. -->

    <array name ="config_displayWhiteBalanceLowLightAmbientBrightnesses">

        <item>10.0</item>

        <item>10.0</item>

    </array>



    <!-- See DisplayWhiteBalanceController.

         An array containing a list of biases. See

         config_displayWhiteBalanceLowLightAmbientBrightnesses for additional details.

         This array must be in the range of [0.0, 1.0]. -->

    <array name ="config_displayWhiteBalanceLowLightAmbientBiases">

        <item>0.0</item>

        <item>1.0</item>

    </array>



    <!-- See DisplayWhiteBalanceController.

         The ambient color temperature (in cct) to which we fall back when the ambient brightness

core/res/res/values/symbols.xml

+2 −1
Original line number Diff line number Diff line
@@ -3745,7 +3745,8 @@ 
  <java-symbol type="array" name="config_displayWhiteBalanceBaseThresholds" />

  <java-symbol type="array" name="config_displayWhiteBalanceIncreaseThresholds" />

  <java-symbol type="array" name="config_displayWhiteBalanceDecreaseThresholds" />

  <java-symbol type="dimen" name="config_displayWhiteBalanceLowLightAmbientBrightnessThreshold" />

  <java-symbol type="array" name="config_displayWhiteBalanceLowLightAmbientBrightnesses" />

  <java-symbol type="array" name="config_displayWhiteBalanceLowLightAmbientBiases" />

  <java-symbol type="dimen" name="config_displayWhiteBalanceLowLightAmbientColorTemperature" />

  <java-symbol type="array" name="config_displayWhiteBalanceAmbientColorTemperatures" />

  <java-symbol type="array" name="config_displayWhiteBalanceDisplayColorTemperatures" />

services/core/java/com/android/server/display/whitebalance/AmbientFilter.java

+3 −1
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ package com.android.server.display.whitebalance; 


import android.util.Slog;



import com.android.internal.annotations.VisibleForTesting;

import com.android.server.display.utils.RollingBuffer;



import java.io.PrintWriter;
@@ -155,7 +156,8 @@ abstract class AmbientFilter { 
    /**

     * A weighted average prioritising recent changes.

     */

    static class WeightedMovingAverageAmbientFilter extends AmbientFilter {

    @VisibleForTesting

    public static class WeightedMovingAverageAmbientFilter extends AmbientFilter {



        // How long the latest ambient value change is predicted to last.

        private static final int PREDICTION_TIME = 100; // Milliseconds

services/core/java/com/android/server/display/whitebalance/DisplayWhiteBalanceController.java

+42 −19
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ import android.annotation.NonNull; 
import android.util.Slog;

import android.util.Spline;



import com.android.internal.annotations.VisibleForTesting;

import com.android.internal.util.Preconditions;

import com.android.server.LocalServices;

import com.android.server.display.color.ColorDisplayService.ColorDisplayServiceInternal;
@@ -53,18 +54,21 @@ public class DisplayWhiteBalanceController implements 
    private Callbacks mCallbacks;



    private AmbientSensor.AmbientBrightnessSensor mBrightnessSensor;

    private AmbientFilter mBrightnessFilter;



    @VisibleForTesting

    AmbientFilter mBrightnessFilter;

    private AmbientSensor.AmbientColorTemperatureSensor mColorTemperatureSensor;

    private AmbientFilter mColorTemperatureFilter;



    @VisibleForTesting

    AmbientFilter mColorTemperatureFilter;

    private DisplayWhiteBalanceThrottler mThrottler;



    // When the brightness drops below a certain threshold, it affects the color temperature

    // accuracy, so we fall back to a fixed ambient color temperature.

    private final float mLowLightAmbientBrightnessThreshold;

    private final float mLowLightAmbientColorTemperature;



    private float mAmbientColorTemperature;

    private float mPendingAmbientColorTemperature;



    @VisibleForTesting

    float mPendingAmbientColorTemperature;

    private float mLastAmbientColorTemperature;



    private ColorDisplayServiceInternal mColorDisplayServiceInternal;
@@ -79,6 +83,9 @@ public class DisplayWhiteBalanceController implements 
    // A piecewise linear relationship between ambient and display color temperatures.

    private Spline.LinearSpline mAmbientToDisplayColorTemperatureSpline;



    // A piecewise linear relationship between low light brightness and low light bias.

    private Spline.LinearSpline mLowLightAmbientBrightnessToBiasSpline;



    /**

     * @param brightnessSensor

     *      The sensor used to detect changes in the ambient brightness.
@@ -119,7 +126,8 @@ public class DisplayWhiteBalanceController implements 
            @NonNull AmbientSensor.AmbientColorTemperatureSensor colorTemperatureSensor,

            @NonNull AmbientFilter colorTemperatureFilter,

            @NonNull DisplayWhiteBalanceThrottler throttler,

            float lowLightAmbientBrightnessThreshold, float lowLightAmbientColorTemperature,

            float[] lowLightAmbientBrightnesses, float[] lowLightAmbientBiases,

            float lowLightAmbientColorTemperature,

            float[] ambientColorTemperatures, float[] displayColorTemperatures) {

        validateArguments(brightnessSensor, brightnessFilter, colorTemperatureSensor,

                colorTemperatureFilter, throttler);
@@ -131,7 +139,6 @@ public class DisplayWhiteBalanceController implements 
        mColorTemperatureSensor = colorTemperatureSensor;

        mColorTemperatureFilter = colorTemperatureFilter;

        mThrottler = throttler;

        mLowLightAmbientBrightnessThreshold = lowLightAmbientBrightnessThreshold;

        mLowLightAmbientColorTemperature = lowLightAmbientColorTemperature;

        mAmbientColorTemperature = -1.0f;

        mPendingAmbientColorTemperature = -1.0f;
@@ -139,10 +146,28 @@ public class DisplayWhiteBalanceController implements 
        mAmbientColorTemperatureHistory = new History(HISTORY_SIZE);

        mAmbientColorTemperatureOverride = -1.0f;



        try {

            mLowLightAmbientBrightnessToBiasSpline = new Spline.LinearSpline(

                    lowLightAmbientBrightnesses, lowLightAmbientBiases);

        } catch (Exception e) {

            Slog.e(TAG, "failed to create low light ambient brightness to bias spline.", e);

            mLowLightAmbientBrightnessToBiasSpline = null;

        }

        if (mLowLightAmbientBrightnessToBiasSpline != null) {

            if (mLowLightAmbientBrightnessToBiasSpline.interpolate(0.0f) != 0.0f ||

                    mLowLightAmbientBrightnessToBiasSpline.interpolate(Float.POSITIVE_INFINITY)

                    != 1.0f) {

                Slog.d(TAG, "invalid low light ambient brightness to bias spline, "

                        + "bias must begin at 0.0 and end at 1.0");

                mLowLightAmbientBrightnessToBiasSpline = null;

            }

        }



        try {

            mAmbientToDisplayColorTemperatureSpline = new Spline.LinearSpline(

                    ambientColorTemperatures, displayColorTemperatures);

        } catch (Exception e) {

            Slog.e(TAG, "failed to create ambient to display color temperature spline.", e);

            mAmbientToDisplayColorTemperatureSpline = null;

        }
@@ -238,8 +263,6 @@ public class DisplayWhiteBalanceController implements 
        mColorTemperatureSensor.dump(writer);

        mColorTemperatureFilter.dump(writer);

        mThrottler.dump(writer);

        writer.println("  mLowLightAmbientBrightnessThreshold="

                + mLowLightAmbientBrightnessThreshold);

        writer.println("  mLowLightAmbientColorTemperature=" + mLowLightAmbientColorTemperature);

        writer.println("  mAmbientColorTemperature=" + mAmbientColorTemperature);

        writer.println("  mPendingAmbientColorTemperature=" + mPendingAmbientColorTemperature);
@@ -248,6 +271,8 @@ public class DisplayWhiteBalanceController implements 
        writer.println("  mAmbientColorTemperatureOverride=" + mAmbientColorTemperatureOverride);

        writer.println("  mAmbientToDisplayColorTemperatureSpline="

                + mAmbientToDisplayColorTemperatureSpline);

        writer.println("  mLowLightAmbientBrightnessToBiasSpline="

                + mLowLightAmbientBrightnessToBiasSpline);

    }



    @Override // AmbientSensor.AmbientBrightnessSensor.Callbacks
@@ -276,15 +301,13 @@ public class DisplayWhiteBalanceController implements 
                mAmbientToDisplayColorTemperatureSpline.interpolate(ambientColorTemperature);

        }



        final float ambientBrightness = mBrightnessFilter.getEstimate(time);

        if (ambientBrightness < mLowLightAmbientBrightnessThreshold) {

            if (mLoggingEnabled) {

                Slog.d(TAG, "low light ambient brightness: " + ambientBrightness + " < "

                        + mLowLightAmbientBrightnessThreshold

                        + ", falling back to fixed ambient color temperature: "

                        + ambientColorTemperature + " => " + mLowLightAmbientColorTemperature);

            }

            ambientColorTemperature = mLowLightAmbientColorTemperature;

        float ambientBrightness = mBrightnessFilter.getEstimate(time);



        if (mLowLightAmbientBrightnessToBiasSpline != null) {

            float bias = mLowLightAmbientBrightnessToBiasSpline.interpolate(ambientBrightness);

            ambientColorTemperature =

                    bias * ambientColorTemperature + (1.0f - bias)

                    * mLowLightAmbientColorTemperature;

        }



        if (mAmbientColorTemperatureOverride != -1.0f) {

services/core/java/com/android/server/display/whitebalance/DisplayWhiteBalanceFactory.java

+8 −4
Original line number Diff line number Diff line
@@ -63,9 +63,12 @@ public class DisplayWhiteBalanceFactory { 
                createColorTemperatureSensor(handler, sensorManager, resources);

        final AmbientFilter colorTemperatureFilter = createColorTemperatureFilter(resources);

        final DisplayWhiteBalanceThrottler throttler = createThrottler(resources);

        final float lowLightAmbientBrightnessThreshold = getFloat(resources,

                com.android.internal.R.dimen

                .config_displayWhiteBalanceLowLightAmbientBrightnessThreshold);

        final float[] displayWhiteBalanceLowLightAmbientBrightnesses = getFloatArray(resources,

                com.android.internal.R.array

                .config_displayWhiteBalanceLowLightAmbientBrightnesses);

        final float[] displayWhiteBalanceLowLightAmbientBiases = getFloatArray(resources,

                com.android.internal.R.array

                .config_displayWhiteBalanceLowLightAmbientBiases);

        final float lowLightAmbientColorTemperature = getFloat(resources,

                com.android.internal.R.dimen

                .config_displayWhiteBalanceLowLightAmbientColorTemperature);
@@ -75,7 +78,8 @@ public class DisplayWhiteBalanceFactory { 
                com.android.internal.R.array.config_displayWhiteBalanceDisplayColorTemperatures);

        final DisplayWhiteBalanceController controller = new DisplayWhiteBalanceController(

                brightnessSensor, brightnessFilter, colorTemperatureSensor, colorTemperatureFilter,

                throttler, lowLightAmbientBrightnessThreshold, lowLightAmbientColorTemperature,

                throttler, displayWhiteBalanceLowLightAmbientBrightnesses,

                displayWhiteBalanceLowLightAmbientBiases, lowLightAmbientColorTemperature,

                ambientColorTemperatures, displayColorTempeartures);

        brightnessSensor.setCallbacks(controller);

        colorTemperatureSensor.setCallbacks(controller);