The gamut will contain the full range of color notes that can be mixed from a given set of starting colors. Those starting colors could be the paint pigments you choose for a limited palette. Or they might be a set of custom starting colors, called color strings, which you premix with a palette knife.
Any triangular gamut has three primaries, one in each corner of the triangle. These are called subjective primaries, because they may not correspond at all with the full-intensity colors we may think of as primary colors. Yet they are the purest and most extreme colors within the gamut you’ve selected.
Note that in the cool gamut above, the purest "yellow" is a warm gray, a mixture of the weak red-magenta and the weak green-cyan. So what looks "yellow" on the Las Vegas sign is really just that warm gray.
Premixing is the key to staying within the gamut you want. You define the range of colors, then you mix those colors and use no others. That way, you’ll get exactly the range you want.
Gamut planning becomes especially important for sequential artists, such as book illustrators or comic artists, or for concept artists or game designers. It's a tremendous aid for painting color ranges like those above. Those skin tones on the top image of Gandalf are in ranges that most traditional painters aren’t used to mixing. (From The Lord of the Rings, directed by Peter Jackson, ©New Line Cinema, all rights reserved.)
This method is also a good tool for gallery painters. You can bring plein air paintings home and develop them into studio compositions with interesting moods. By placing a gamut mask over the color wheel, you can define a very specific range of color for your painting. Tomorrow I’ll show you the method in action with those two Las Vegas paintings.
You can order the book "Color and Light" by mail from my online store and get it signed.
Read the full series
Gamut Masking, Part 1
Gamut Masking, Part 2
Colored Cube Illusion (aka "Color Constancy")
2008 post on color masking