Let’s see how the gamut masking (or "mapping") method actually works, using the example of that bright colored Las Vegas scene.
This video walks you through it, step by step.
(Video Link) By comparing the three paintings below, you can see how the two smaller paintings were shifted to the warm and cool.
Note that underneath each of the two shifted paintings is a set of nine swatches. Those are the subjective primaries carried through three values each. Each of the paintings was done with those carefully limited subjective primaries, leaving aside the tube colors. Note also that two of those primaries are the same: the green-cyan, and the red-magenta.
The wild card is the yellow in the top one and the blue in the bottom one.
Now look at those three swatches connected by arrows. The color note that appears as the blue sky in the warm scene is almost exactly the same color as the color that appears yellow in the cool painting. Both are basically a neutral gray. It’s a subjective secondary belonging to each of the two gamuts.
I’ve out lifted those swatches out of the smaller paintings so that you can see how they look out of context. I’ve also lifted a swatch of the “yellow” from the cool painting and put it over the yellow shoe in the original painting.
It’s hard to believe that a neutral gray could appear either blue or yellow.
These are weird mixtures, and you wouldn’t think of using them unless you forced yourself with the gamut masking system.
This is reminiscent of the colored cube illusion we’ve seen before, where the red and cyan squares look different, but they’re both really the same gray.
This little demo will be part of an article that I wrote, which will be appearing in the upcoming fall print issue of American Artist’s Plein Air Painting magazine.
Previously on GJ:
Gamut Masking, Part 1
Gamut Masking, Part 2
Colored Cube Illusion (aka "Color Constancy")
2008 post on color masking
A free online gamut masking tool for digitally minded artists by Richard Robinson
You can order the book "Color and Light" by mail from my online store.