static Rect autoCropOfRGBImage_blackBG(RGBImage img) {
  ret autoCropOfBWImage_blackBG(new BWImage(img));
}

static Rect autoCropOfRGBImage_blackBG(RGBImage img, Rect r) {
  ret autoCropOfBWImage_blackBG(new BWImage(img), r);
}