@VisibleForTesting
  static int luminance(@ColorInt int color) {
    double r = Color.red(color) * 0.2126;
    double g = Color.green(color) * 0.7152;
    double b = Color.blue(color) * 0.0722;

    return (int) Math.ceil(r + g + b);
  }
@Test
  public void testLuminance() {
    Assert.assertEquals(255, OverlayDataNormalizer.luminance(Color.WHITE));
    Assert.assertEquals(0, OverlayDataNormalizer.luminance(Color.BLACK));
    Assert.assertEquals(136, OverlayDataNormalizer.luminance(Color.GRAY));
    Assert.assertEquals(19, OverlayDataNormalizer.luminance(Color.BLUE));
    Assert.assertEquals(183, OverlayDataNormalizer.luminance(Color.GREEN));
    Assert.assertEquals(55, OverlayDataNormalizer.luminance(Color.RED));
    Assert.assertEquals(73, OverlayDataNormalizer.luminance(Color.MAGENTA));
  }