static RGBImage rgbContrastAndBrightness(RGBImage img, float scaleFactor, float offset) {
  BufferedImage img = cloneBufferedImage(img.getBufferedImage());
  new RescaleOp(scaleFactor, offset, null).filter(img, img);
  ret img;
}

static RGBImage rgbContrastAndBrightness(float scaleFactor, float offset, RGBImage img) {
  ret rgbContrastAndBrightness(img, scaleFactor, offset);
}