!7

static int cn = 3, cw = 20;

p {
  RGBImage rgb = new RGBImage(inputImage());
  int w = rgb.w();
  float[] data = new float[w];
  for x to w:
    data[x] = rgbContrast(rgbCol(rgb, x));
  showImageWithHorizontalGraph(rgb, data);
}