@Override
  public String toString() {
    return "ToonFilterTransformation(threshold=" + threshold + ",quantizationLevels="
      + quantizationLevels + ")";
  }
The threshold at which to apply the edges, default of 0.2.
The levels of quantization for the posterization of colors within the scene,
with a default of 10.0.
transformations/src/main/java/jp/wasabeef/glide/transformations/gpu/ToonFilterTransformation.java