setRGBWeights(1, 0, 0);
  getStatistics(area, mean, rmin, rmax);
  setRGBWeights(0, 1, 0);
  getStatistics(area, mean, gmin, gmax);
  setRGBWeights(0, 0, 1);
  getStatistics(area, mean, bmin, bmax);
  min = maxOf(maxOf(rmin,gmin),bmin);
  max = minOf(maxOf(rmax,gmax),bmax);
  run("Subtract...", "value=&min");
  scale = 255/(max-min);
  run("Multiply...", "value=&scale");