private CloseableReference<Bitmap> createRainbowBitmap() {
    final int w = 256;
    final int h = 256;
    mOriginalBitmap = mPlatformBitmapFactory.createBitmap(w, h, Bitmap.Config.ARGB_8888);

    final int[] colors = new int[w * h];
    for (int i = 0; i < w; i++) {
      for (int j = 0; j < h; j++) {
        final float hue = 360f * j / (float) w;
        final float saturation = 2f * (h - i) / (float) h;
        final float value = 1;
        colors[i * h + j] = Color.HSVToColor(255, new float[] {hue, saturation, value});
      }
    }
    mOriginalBitmap.get().setPixels(colors, 0, w, 0, 0, w, h);

    return mOriginalBitmap;
  }
Creates a new bitmap with a HSV map at value=1
samples/showcase/src/main/java/com/facebook/fresco/samples/showcase/imagepipeline/ImagePipelineBitmapFactoryFragment.java