@Override
  public int hashCode() {
    return ID.hashCode() + center.hashCode() + Arrays.hashCode(vignetteColor) +
      (int) (vignetteStart * 100) + (int) (vignetteEnd * 10);
  }
Performs a vignetting effect, fading out the image at the edges
The directional intensity of the vignetting,
with a default of x = 0.5, y = 0.5, start = 0, end = 0.75
transformations/src/main/java/jp/wasabeef/glide/transformations/gpu/VignetteFilterTransformation.java