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

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

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