Add OETF and EOTF ES2 fragment shaders for non-HDR frames.

* Transform the intermediate color space to linear SDR by applying the SMPTE 170M EOTF and OETF.
* Use linear colors for the color filter pixel tests and update all golden bitmaps.

PiperOrigin-RevId: 476124592
(cherry picked from commit 3433758c3b1f02c0ec28b86a8c3b659171f6f92b)

libraries/effect/src/androidTest/java/androidx/media3/effect/ContrastPixelTest.java

@@ -48,13 +48,13 @@ import org.junit.runner.RunWith;
 @RunWith(AndroidJUnit4.class)
 public class ContrastPixelTest {
   public static final String ORIGINAL_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/original.png";
+      "media/bitmap/sample_mp4_first_frame/linear_colors/original.png";
   public static final String INCREASE_CONTRAST_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/increase_contrast.png";
+      "media/bitmap/sample_mp4_first_frame/linear_colors/increase_contrast.png";
   public static final String DECREASE_CONTRAST_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/decrease_contrast.png";
+      "media/bitmap/sample_mp4_first_frame/linear_colors/decrease_contrast.png";
   public static final String MAXIMUM_CONTRAST_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/maximum_contrast.png";
+      "media/bitmap/sample_mp4_first_frame/linear_colors/maximum_contrast.png";
 
   // OpenGL uses floats in [0, 1] and maps 0.5f to 128 = 256 / 2.
   private static final int OPENGL_NEUTRAL_RGB_VALUE = 128;

libraries/effect/src/androidTest/java/androidx/media3/effect/CropPixelTest.java

@@ -47,11 +47,11 @@ import org.junit.runner.RunWith;
 @RunWith(AndroidJUnit4.class)
 public final class CropPixelTest {
   public static final String ORIGINAL_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/original.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/original.png";
   public static final String CROP_SMALLER_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/crop_smaller.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/crop_smaller.png";
   public static final String CROP_LARGER_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/crop_larger.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/crop_larger.png";
 
   private final Context context = getApplicationContext();
 

libraries/effect/src/androidTest/java/androidx/media3/effect/GlEffectsFrameProcessorPixelTest.java

@@ -58,27 +58,27 @@ import org.junit.runner.RunWith;
 @RunWith(AndroidJUnit4.class)
 public final class GlEffectsFrameProcessorPixelTest {
   public static final String ORIGINAL_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/original.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/original.png";
   public static final String SCALE_WIDE_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/scale_wide.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/scale_wide.png";
   public static final String TRANSLATE_RIGHT_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/translate_right.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/translate_right.png";
   public static final String ROTATE_THEN_TRANSLATE_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/rotate_then_translate.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/rotate_then_translate.png";
   public static final String ROTATE_THEN_SCALE_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/rotate45_then_scale2w.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/rotate45_then_scale2w.png";
   public static final String TRANSLATE_THEN_ROTATE_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/translate_then_rotate.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/translate_then_rotate.png";
   public static final String REQUEST_OUTPUT_HEIGHT_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/request_output_height.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/request_output_height.png";
   public static final String CROP_THEN_ASPECT_RATIO_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/crop_then_aspect_ratio.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/crop_then_aspect_ratio.png";
   public static final String ROTATE45_SCALE_TO_FIT_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/rotate_45_scale_to_fit.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/rotate_45_scale_to_fit.png";
   public static final String INCREASE_BRIGHTNESS_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/increase_brightness.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/increase_brightness.png";
   public static final String GRAYSCALE_THEN_INCREASE_RED_CHANNEL_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/grayscale_then_increase_red_channel.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/grayscale_then_increase_red_channel.png";
 
   /** Input video of which we only use the first frame. */
   private static final String INPUT_MP4_ASSET_STRING = "media/mp4/sample.mp4";

libraries/effect/src/androidTest/java/androidx/media3/effect/MatrixTextureProcessorPixelTest.java

@@ -46,13 +46,13 @@ import org.junit.runner.RunWith;
 @RunWith(AndroidJUnit4.class)
 public final class MatrixTextureProcessorPixelTest {
   public static final String ORIGINAL_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/original.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/original.png";
   public static final String TRANSLATE_RIGHT_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/translate_right.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/translate_right.png";
   public static final String SCALE_NARROW_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/scale_narrow.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/scale_narrow.png";
   public static final String ROTATE_90_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/rotate90.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/rotate90.png";
 
   private final Context context = getApplicationContext();
 

libraries/effect/src/androidTest/java/androidx/media3/effect/PresentationPixelTest.java

@@ -48,19 +48,19 @@ import org.junit.runner.RunWith;
 @RunWith(AndroidJUnit4.class)
 public final class PresentationPixelTest {
   public static final String ORIGINAL_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/original.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/original.png";
   public static final String ASPECT_RATIO_SCALE_TO_FIT_NARROW_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/aspect_ratio_scale_to_fit_narrow.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/aspect_ratio_scale_to_fit_narrow.png";
   public static final String ASPECT_RATIO_SCALE_TO_FIT_WIDE_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/aspect_ratio_scale_to_fit_wide.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/aspect_ratio_scale_to_fit_wide.png";
   public static final String ASPECT_RATIO_SCALE_TO_FIT_WITH_CROP_NARROW_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/aspect_ratio_scale_to_fit_with_crop_narrow.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/aspect_ratio_scale_to_fit_with_crop_narrow.png";
   public static final String ASPECT_RATIO_SCALE_TO_FIT_WITH_CROP_WIDE_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/aspect_ratio_scale_to_fit_with_crop_wide.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/aspect_ratio_scale_to_fit_with_crop_wide.png";
   public static final String ASPECT_RATIO_STRETCH_TO_FIT_NARROW_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/aspect_ratio_stretch_to_fit_narrow.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/aspect_ratio_stretch_to_fit_narrow.png";
   public static final String ASPECT_RATIO_STRETCH_TO_FIT_WIDE_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/aspect_ratio_stretch_to_fit_wide.png";
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/aspect_ratio_stretch_to_fit_wide.png";
 
   private final Context context = getApplicationContext();
 

libraries/effect/src/androidTest/java/androidx/media3/effect/RgbAdjustmentPixelTest.java

@@ -50,13 +50,13 @@ import org.junit.runner.RunWith;
 @RunWith(AndroidJUnit4.class)
 public final class RgbAdjustmentPixelTest {
   public static final String ORIGINAL_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/original.png";
+      "media/bitmap/sample_mp4_first_frame/linear_colors/original.png";
   public static final String ONLY_RED_CHANNEL_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/only_red_channel.png";
+      "media/bitmap/sample_mp4_first_frame/linear_colors/only_red_channel.png";
   public static final String INCREASE_RED_CHANNEL_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/increase_red_channel.png";
+      "media/bitmap/sample_mp4_first_frame/linear_colors/increase_red_channel.png";
   public static final String INCREASE_BRIGHTNESS_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/increase_brightness.png";
+      "media/bitmap/sample_mp4_first_frame/linear_colors/increase_brightness.png";
 
   private final Context context = getApplicationContext();
 

libraries/effect/src/androidTest/java/androidx/media3/effect/RgbFilterPixelTest.java

@@ -48,11 +48,11 @@ import org.junit.runner.RunWith;
 @RunWith(AndroidJUnit4.class)
 public final class RgbFilterPixelTest {
   public static final String ORIGINAL_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/original.png";
+      "media/bitmap/sample_mp4_first_frame/linear_colors/original.png";
   public static final String GRAYSCALE_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/grayscale.png";
+      "media/bitmap/sample_mp4_first_frame/linear_colors/grayscale.png";
   public static final String INVERT_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/invert.png";
+      "media/bitmap/sample_mp4_first_frame/linear_colors/invert.png";
 
   private final Context context = getApplicationContext();
 

libraries/effect/src/androidTest/java/androidx/media3/effect/SingleColorLutPixelTest.java

@@ -48,13 +48,13 @@ import org.junit.runner.RunWith;
 @RunWith(AndroidJUnit4.class)
 public class SingleColorLutPixelTest {
   public static final String ORIGINAL_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/original.png";
+      "media/bitmap/sample_mp4_first_frame/linear_colors/original.png";
   public static final String LUT_MAP_WHITE_TO_GREEN_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/lut_map_white_to_green.png";
+      "media/bitmap/sample_mp4_first_frame/linear_colors/lut_map_white_to_green.png";
   public static final String GRAYSCALE_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/grayscale.png";
+      "media/bitmap/sample_mp4_first_frame/linear_colors/grayscale.png";
   public static final String INVERT_PNG_ASSET_PATH =
-      "media/bitmap/sample_mp4_first_frame/invert.png";
+      "media/bitmap/sample_mp4_first_frame/linear_colors/invert.png";
   public static final String VERTICAL_HALD_IDENTITY_LUT = "media/bitmap/lut/identity.png";
   public static final String VERTICAL_HALD_GRAYSCALE_LUT = "media/bitmap/lut/grayscale.png";
   public static final String VERTICAL_HALD_INVERTED_LUT = "media/bitmap/lut/inverted.png";

libraries/effect/src/main/assets/shaders/fragment_shader_transformation_external_es2.glsl

@@ -1,30 +0,0 @@
-#version 100
-// Copyright 2021 The Android Open Source Project
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// ES 2 fragment shader that samples from an external texture with uTexSampler,
-// copying from this texture to the current output while applying a 4x4 RGB
-// color matrix to change the pixel colors.
-
-#extension GL_OES_EGL_image_external : require
-precision mediump float;
-uniform samplerExternalOES uTexSampler;
-uniform mat4 uRgbMatrix;
-varying vec2 vTexSamplingCoord;
-
-void main() {
-  vec4 inputColor = texture2D(uTexSampler, vTexSamplingCoord);
-  gl_FragColor = uRgbMatrix * vec4(inputColor.rgb, 1);
-  gl_FragColor.a = inputColor.a;
-}

libraries/effect/src/main/assets/shaders/fragment_shader_transformation_external_yuv_es3.glsl

@@ -104,4 +104,5 @@ void main() {
   vec3 srcYuv = texture(uTexSampler, vTexSamplingCoord).xyz;
   vec3 rgb = yuvToRgb(srcYuv);
   outColor = uRgbMatrix * vec4(getOpticalColor(rgb), 1.0);
+  // TODO(b/241902517): Transform optical to electrical colors.
 }

libraries/effect/src/main/assets/shaders/fragment_shader_transformation_sdr_external_es2.glsl

@@ -0,0 +1,79 @@
+#version 100
+// Copyright 2021 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+
+// ES 2 fragment shader that:
+// 1. Samples from an external texture with uTexSampler copying from this
+//    texture to the current output.
+// 2. Transforms the electrical colors to optical colors using the SMPTE 170M
+//    EOTF.
+// 3. Applies a 4x4 RGB color matrix to change the pixel colors.
+// 4. Transforms the optical colors back to electrical ones if uApplyOetf == 1
+//    using the SMPTE 170M OETF.
+
+#extension GL_OES_EGL_image_external : require
+precision mediump float;
+uniform samplerExternalOES uTexSampler;
+uniform mat4 uRgbMatrix;
+varying vec2 vTexSamplingCoord;
+uniform int uApplyOetf;
+
+const float inverseGamma = 0.4500;
+const float gamma = 1.0 / inverseGamma;
+
+// Transforms a single channel from electrical to optical SDR.
+float sdrEotfSingleChannel(float electricalChannel) {
+  // Specification:
+  // https://www.itu.int/rec/R-REC-BT.1700-0-200502-I/en
+  return electricalChannel < 0.0812
+    ? electricalChannel / 4.500
+    : pow((electricalChannel + 0.099) / 1.099, gamma);
+}
+
+// Transforms electronical to optical SDR using the SMPTE 170M EOTF.
+vec3 sdrEotf(vec3 electricalColor) {
+  return vec3(
+    sdrEotfSingleChannel(electricalColor.r),
+    sdrEotfSingleChannel(electricalColor.g),
+    sdrEotfSingleChannel(electricalColor.b));
+}
+
+// Transforms a single channel from optical to electrical SDR.
+float sdrOetfSingleChannel(float opticalChannel) {
+  // Specification:
+  // https://www.itu.int/rec/R-REC-BT.1700-0-200502-I/en
+  return opticalChannel < 0.018
+    ? opticalChannel * 4.500
+    : 1.099 * pow(opticalChannel, inverseGamma) - 0.099;
+}
+
+// Transforms optical SDR colors to electrical SDR using the SMPTE 170M OETF.
+vec3 sdrOetf(vec3 opticalColor) {
+  return uApplyOetf == 1
+    ? vec3(
+      sdrOetfSingleChannel(opticalColor.r),
+      sdrOetfSingleChannel(opticalColor.g),
+      sdrOetfSingleChannel(opticalColor.b))
+    : opticalColor;
+}
+
+void main() {
+  vec4 inputColor = texture2D(uTexSampler, vTexSamplingCoord);
+  vec3 linearInputColor = sdrEotf(inputColor.rgb);
+
+  vec4 transformedColors = uRgbMatrix * vec4(linearInputColor, 1);
+
+  gl_FragColor = vec4(sdrOetf(transformedColors.rgb), inputColor.a);
+}

libraries/effect/src/main/assets/shaders/fragment_shader_transformation_sdr_oetf_es2.glsl

@@ -0,0 +1,52 @@
+#version 100
+// Copyright 2022 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// ES 2 fragment shader that:
+// 1. Samples from uTexSampler, copying from this texture to the current
+//    output.
+// 2. Applies a 4x4 RGB color matrix to change the pixel colors.
+// 3. Transforms the optical colors to electrical colors using the SMPTE
+//    170M OETF.
+
+precision mediump float;
+uniform sampler2D uTexSampler;
+uniform mat4 uRgbMatrix;
+varying vec2 vTexSamplingCoord;
+
+const float inverseGamma = 0.4500;
+
+// Transforms a single channel from optical to electrical SDR.
+float sdrOetfSingleChannel(float opticalChannel) {
+    // Specification:
+    // https://www.itu.int/rec/R-REC-BT.1700-0-200502-I/en
+    return opticalChannel < 0.018
+        ? opticalChannel * 4.500
+        : 1.099 * pow(opticalChannel, inverseGamma) - 0.099;
+}
+
+// Transforms optical SDR colors to electrical SDR using the SMPTE 170M OETF.
+vec3 sdrOetf(vec3 opticalColor) {
+    return vec3(
+        sdrOetfSingleChannel(opticalColor.r),
+        sdrOetfSingleChannel(opticalColor.g),
+        sdrOetfSingleChannel(opticalColor.b));
+}
+
+void main() {
+    vec4 inputColor = texture2D(uTexSampler, vTexSamplingCoord);
+    vec4 transformedColors = uRgbMatrix * vec4(inputColor.rgb, 1);
+
+    gl_FragColor = vec4(sdrOetf(transformedColors.rgb), inputColor.a);
+}

libraries/effect/src/main/java/androidx/media3/effect/MatrixTextureProcessor.java

@@ -50,6 +50,7 @@ import java.util.List;
  *
  * <p>Can copy frames from an external texture and apply color transformations for HDR if needed.
  */
+// TODO(b/241902517): Fix Gamma references since intermediate color space is now linear.
 @UnstableApi
 @SuppressWarnings("FunctionalInterfaceClash") // b/228192298
 /* package */ final class MatrixTextureProcessor extends SingleFrameGlTextureProcessor
@@ -63,10 +64,12 @@ import java.util.List;
       "shaders/fragment_shader_transformation_es2.glsl";
   private static final String FRAGMENT_SHADER_OETF_ES3_PATH =
       "shaders/fragment_shader_oetf_es3.glsl";
-  private static final String FRAGMENT_SHADER_TRANSFORMATION_EXTERNAL_PATH =
-      "shaders/fragment_shader_transformation_external_es2.glsl";
+  private static final String FRAGMENT_SHADER_TRANSFORMATION_SDR_OETF_ES2_PATH =
+      "shaders/fragment_shader_transformation_sdr_oetf_es2.glsl";
   private static final String FRAGMENT_SHADER_TRANSFORMATION_EXTERNAL_YUV_ES3_PATH =
       "shaders/fragment_shader_transformation_external_yuv_es3.glsl";
+  private static final String FRAGMENT_SHADER_TRANSFORMATION_SDR_EXTERNAL_PATH =
+      "shaders/fragment_shader_transformation_sdr_external_es2.glsl";
   private static final ImmutableList<float[]> NDC_SQUARE =
       ImmutableList.of(
           new float[] {-1, -1, 0, 1},
@@ -152,6 +155,7 @@ import java.util.List;
             context, VERTEX_SHADER_TRANSFORMATION_PATH, FRAGMENT_SHADER_TRANSFORMATION_PATH);
 
     // No transfer functions needed, because input and output are both optical colors.
+    // TODO(b/241902517): Add transfer functions since existing color filters may change the colors.
     return new MatrixTextureProcessor(
         glProgram,
         ImmutableList.copyOf(matrixTransformations),
@@ -194,10 +198,9 @@ import java.util.List;
     String fragmentShaderFilePath =
         useHdr
             ? FRAGMENT_SHADER_TRANSFORMATION_EXTERNAL_YUV_ES3_PATH
-            : FRAGMENT_SHADER_TRANSFORMATION_EXTERNAL_PATH;
+            : FRAGMENT_SHADER_TRANSFORMATION_SDR_EXTERNAL_PATH;
     GlProgram glProgram = createGlProgram(context, vertexShaderFilePath, fragmentShaderFilePath);
 
-    // TODO(b/241902517): Implement gamma transfer functions.
     if (useHdr) {
       // In HDR editing mode the decoder output is sampled in YUV.
       if (!GlUtil.isYuvTargetExtensionSupported()) {
@@ -214,6 +217,8 @@ import java.util.List;
       checkArgument(
           colorTransfer == C.COLOR_TRANSFER_HLG || colorTransfer == C.COLOR_TRANSFER_ST2084);
       glProgram.setIntUniform("uEotfColorTransfer", colorTransfer);
+    } else {
+      glProgram.setIntUniform("uApplyOetf", 0);
     }
 
     return new MatrixTextureProcessor(
@@ -252,10 +257,9 @@ import java.util.List;
     String vertexShaderFilePath =
         useHdr ? VERTEX_SHADER_TRANSFORMATION_ES3_PATH : VERTEX_SHADER_TRANSFORMATION_PATH;
     String fragmentShaderFilePath =
-        useHdr ? FRAGMENT_SHADER_OETF_ES3_PATH : FRAGMENT_SHADER_TRANSFORMATION_PATH;
+        useHdr ? FRAGMENT_SHADER_OETF_ES3_PATH : FRAGMENT_SHADER_TRANSFORMATION_SDR_OETF_ES2_PATH;
     GlProgram glProgram = createGlProgram(context, vertexShaderFilePath, fragmentShaderFilePath);
 
-    // TODO(b/241902517): Implement gamma transfer functions.
     if (useHdr) {
       @C.ColorTransfer int colorTransfer = electricalColorInfo.colorTransfer;
       checkArgument(
@@ -277,7 +281,7 @@ import java.util.List;
    * #setTextureTransformMatrix(float[])} to provide the transformation matrix associated with the
    * external texture.
    *
-   * <p>Applies the OETF, {@code matrixTransformations}, {@code rgbMatrices}, then the EOTF, to
+   * <p>Applies the EOTF, {@code matrixTransformations}, {@code rgbMatrices}, then the OETF, to
    * convert from and to input and output electrical colors.
    *
    * @param context The {@link Context}.
@@ -301,10 +305,9 @@ import java.util.List;
     String fragmentShaderFilePath =
         useHdr
             ? FRAGMENT_SHADER_TRANSFORMATION_EXTERNAL_YUV_ES3_PATH
-            : FRAGMENT_SHADER_TRANSFORMATION_EXTERNAL_PATH;
+            : FRAGMENT_SHADER_TRANSFORMATION_SDR_EXTERNAL_PATH;
     GlProgram glProgram = createGlProgram(context, vertexShaderFilePath, fragmentShaderFilePath);
 
-    // TODO(b/241902517): Implement gamma transfer functions.
     if (useHdr) {
       // In HDR editing mode the decoder output is sampled in YUV.
       if (!GlUtil.isYuvTargetExtensionSupported()) {
@@ -319,6 +322,8 @@ import java.util.List;
 
       // No transfer functions needed, because the EOTF and OETF cancel out.
       glProgram.setIntUniform("uEotfColorTransfer", Format.NO_VALUE);
+    } else {
+      glProgram.setIntUniform("uApplyOetf", 1);
     }
 
     return new MatrixTextureProcessor(

libraries/test_data/src/test/assets/media/bitmap/README.md

@@ -24,7 +24,7 @@ To generate new "expected" assets:
     ```shell
     adb pull \
     /sdcard/Android/data/androidx.media3.effect.test/cache/drawFrame_rotate90_actual.png \
-    third_party/java_src/android_libs/media/libraries/test_data/src/test/assets/media/bitmap/sample_mp4_first_frame/rotate90.png
+    third_party/java_src/android_libs/media/libraries/test_data/src/test/assets/media/bitmap/sample_mp4_first_frame/electrical_colors/rotate90.png
     ```
 
 <!-- copybara:strip_end -->

libraries/test_data/src/test/assets/media/bitmap/sample_mp4_first_frame/electrical_colors/README.md

@@ -0,0 +1,3 @@
+All the files are in *SMPTE 170M colors* following the
+[ITU Spec](https://www.itu.int/rec/R-REC-BT.1700-0-200502-I/en) per the
+[Android MediaFormat documentation](https://developer.android.com/reference/android/media/MediaFormat#COLOR_TRANSFER_SDR_VIDEO).

libraries/test_data/src/test/assets/media/bitmap/sample_mp4_first_frame/linear_colors/README.md

@@ -0,0 +1,2 @@
+All the files are in *Linear RGB* per the
+[Android MediaFormat documentation](https://developer.android.com/reference/android/media/MediaFormat#COLOR_TRANSFER_LINEAR).

libraries/transformer/src/test/java/androidx/media3/transformer/MssimCalculatorTest.java

@@ -34,7 +34,7 @@ public class MssimCalculatorTest {
 
   @Test
   public void calculateSsim_sameImage() throws Exception {
-    Bitmap bitmap = readBitmap("media/bitmap/sample_mp4_first_frame/original.png");
+    Bitmap bitmap = readBitmap("media/bitmap/sample_mp4_first_frame/linear_colors/original.png");
     byte[] imageLuminosities = bitmapToLuminosityArray(bitmap);
 
     // SSIM equals 1 if the two images match.
@@ -46,10 +46,11 @@ public class MssimCalculatorTest {
 
   @Test
   public void calculateSsim_increasedBrightness() throws Exception {
-    Bitmap refBitmap = readBitmap("media/bitmap/sample_mp4_first_frame/original.png");
-    Bitmap distBitmap = readBitmap("media/bitmap/sample_mp4_first_frame/increase_brightness.png");
+    Bitmap refBitmap = readBitmap("media/bitmap/sample_mp4_first_frame/linear_colors/original.png");
+    Bitmap distBitmap =
+        readBitmap("media/bitmap/sample_mp4_first_frame/linear_colors/increase_brightness.png");
 
-    // SSIM as calculated by ffmpeg: 0.634326 = 63%
+    // SSIM as calculated by ffmpeg: 0.526821 = 52%
 
     assertThat(
             (int)
@@ -59,14 +60,15 @@ public class MssimCalculatorTest {
                         refBitmap.getWidth(),
                         refBitmap.getHeight())
                     * 100))
-        .isEqualTo(63);
+        .isEqualTo(52);
   }
 
   @Test
   public void calculateSsim_withWindowSkipping_similarToWithout() throws Exception {
-    Bitmap referenceBitmap = readBitmap("media/bitmap/sample_mp4_first_frame/original.png");
+    Bitmap referenceBitmap =
+        readBitmap("media/bitmap/sample_mp4_first_frame/linear_colors/original.png");
     Bitmap distortedBitmap =
-        readBitmap("media/bitmap/sample_mp4_first_frame/increase_brightness.png");
+        readBitmap("media/bitmap/sample_mp4_first_frame/linear_colors/increase_brightness.png");
     byte[] referenceLuminosity = bitmapToLuminosityArray(referenceBitmap);
     byte[] distortedLuminosity = bitmapToLuminosityArray(distortedBitmap);