diff --git a/library/transformer/src/androidTest/java/com/google/android/exoplayer2/transformer/SsimHelper.java b/library/transformer/src/androidTest/java/com/google/android/exoplayer2/transformer/SsimHelper.java
index e4e51b8f7d5..0eb3bce3ef1 100644
--- a/library/transformer/src/androidTest/java/com/google/android/exoplayer2/transformer/SsimHelper.java
+++ b/library/transformer/src/androidTest/java/com/google/android/exoplayer2/transformer/SsimHelper.java
@@ -80,8 +80,8 @@ public static double calculate(
         new VideoDecodingWrapper(context, referenceVideoPath, DEFAULT_COMPARISON_INTERVAL);
     VideoDecodingWrapper distortedDecodingWrapper =
         new VideoDecodingWrapper(context, distortedVideoPath, DEFAULT_COMPARISON_INTERVAL);
-    @Nullable int[] referenceLumaBuffer = null;
-    @Nullable int[] distortedLumaBuffer = null;
+    @Nullable byte[] referenceLumaBuffer = null;
+    @Nullable byte[] distortedLumaBuffer = null;
     double accumulatedSsim = 0.0;
     int comparedImagesCount = 0;
     try {
@@ -101,10 +101,10 @@ public static double calculate(
         assertThat(distortedImage.getHeight()).isEqualTo(height);
 
         if (referenceLumaBuffer == null || referenceLumaBuffer.length != width * height) {
-          referenceLumaBuffer = new int[width * height];
+          referenceLumaBuffer = new byte[width * height];
         }
         if (distortedLumaBuffer == null || distortedLumaBuffer.length != width * height) {
-          distortedLumaBuffer = new int[width * height];
+          distortedLumaBuffer = new byte[width * height];
         }
         try {
           accumulatedSsim +=
@@ -134,7 +134,7 @@ public static double calculate(
    * @param lumaChannelBuffer The buffer where the extracted luma values are stored.
    * @return The {@code lumaChannelBuffer} for convenience.
    */
-  private static int[] extractLumaChannelBuffer(Image image, int[] lumaChannelBuffer) {
+  private static byte[] extractLumaChannelBuffer(Image image, byte[] lumaChannelBuffer) {
     // This method is invoked on the main thread.
     // `image` should contain YUV channels.
     Image.Plane[] imagePlanes = image.getPlanes();
@@ -147,8 +147,7 @@ private static int[] extractLumaChannelBuffer(Image image, int[] lumaChannelBuff
     ByteBuffer lumaByteBuffer = lumaPlane.getBuffer();
     for (int y = 0; y < height; y++) {
       for (int x = 0; x < width; x++) {
-        lumaChannelBuffer[y * width + x] =
-            lumaByteBuffer.get(y * rowStride + x * pixelStride) & 0xFF;
+        lumaChannelBuffer[y * width + x] = lumaByteBuffer.get(y * rowStride + x * pixelStride);
       }
     }
     return lumaChannelBuffer;
@@ -364,7 +363,7 @@ private static final class MssimCalculator {
      * @return The MSSIM score between the input images.
      */
     public static double calculate(
-        int[] referenceBuffer, int[] distortedBuffer, int width, int height) {
+        byte[] referenceBuffer, byte[] distortedBuffer, int width, int height) {
       double totalSsim = 0;
       int windowsCount = 0;
 
@@ -451,11 +450,11 @@ private static double getWindowSsim(
 
     /** Returns the mean of the pixels in the window. */
     private static double getMean(
-        int[] pixelBuffer, int bufferIndexOffset, int stride, int windowWidth, int windowHeight) {
+        byte[] pixelBuffer, int bufferIndexOffset, int stride, int windowWidth, int windowHeight) {
       double total = 0;
       for (int y = 0; y < windowHeight; y++) {
         for (int x = 0; x < windowWidth; x++) {
-          total += pixelBuffer[get1dIndex(x, y, stride, bufferIndexOffset)];
+          total += pixelBuffer[get1dIndex(x, y, stride, bufferIndexOffset)] & 0xFF;
         }
       }
       return total / (windowWidth * windowHeight);
@@ -463,8 +462,8 @@ private static double getMean(
 
     /** Calculates the variances and covariance of the pixels in the window for both buffers. */
     private static double[] getVariancesAndCovariance(
-        int[] referenceBuffer,
-        int[] distortedBuffer,
+        byte[] referenceBuffer,
+        byte[] distortedBuffer,
         double referenceMean,
         double distortedMean,
         int bufferIndexOffset,
@@ -477,8 +476,8 @@ private static double[] getVariancesAndCovariance(
       for (int y = 0; y < windowHeight; y++) {
         for (int x = 0; x < windowWidth; x++) {
           int index = get1dIndex(x, y, stride, bufferIndexOffset);
-          double referencePixelDeviation = referenceBuffer[index] - referenceMean;
-          double distortedPixelDeviation = distortedBuffer[index] - distortedMean;
+          double referencePixelDeviation = (referenceBuffer[index] & 0xFF) - referenceMean;
+          double distortedPixelDeviation = (distortedBuffer[index] & 0xFF) - distortedMean;
           referenceVariance += referencePixelDeviation * referencePixelDeviation;
           distortedVariance += distortedPixelDeviation * distortedPixelDeviation;
           referenceDistortedCovariance += referencePixelDeviation * distortedPixelDeviation;