I'm real excited because I've just accidentally stumbled upon a totally different way to adjust colour-contrast in an image. This is a world first publication of the DogboneTechnique® Make a new duplicate layer, set the top layer to Luminosity and bring up the Image>Adjustment>Hue and Saturation box and move the hue slider across the whole spectrum and observe the results. Here's a rough example. Note there is no masking or any other trickiness. . EDIT Latest V3 action including built in instructions.