Additive and Subtractive Color
From what I understand so far, there are two sets of primary colors: one for the additive color system and one for the subtractive.
Additive Color
The primary colors in the additive color system are red, blue and green, which combine to create the secondary colors cyan, magenta and yellow. Mixing all three colors produces white.
Direct light uses additive color, which is why television sets and computer monitors use the RGB (red, green, and blue) color model. Like many people in today’s online world, I’m most familiar with RGB through using web colors.
Subtractive Color
The subtractive color system is essentially the opposite of the additive color system, as you can guess from their names. The primary colors in the subtractive color system are cyan, magenta and yellow, while the secondary colors are red, blue and green. Mixing all three primary colors yields black.
Whereas direct light uses the additive color system, pigments (which absorb light) use the subtractive color system. I used to think that red, blue and yellow were the primary colors, but I recently discovered the truth (see Why Your Art Teacher Lied About Primary Colors). Printing uses the CMYK color model, which saves ink by creating every color through a mixture of cyan, magenta, yellow and black.
There’s a lot more to be said about colors and color models, but I don’t want to stray off topic; most of this stuff deals with math and science more than with art.
