Unified Theory of Color

The way that pigments mix (subtractive color mixing) to produce colors is different from the way that colored lights mix (additive color mixing). The connections between these two systems are elegant if you use cyan, magenta, and yellow as pigment primaries instead of red, yellow, and blue. 

Cyan, magenta, and yellow are the true primary colors for pigment (see blog Reinventing the Wheel: Why Red is not a primary color). These combine to make darker secondary colors red, green and blue, resulting in black when all three pigments are combined. Lights work the opposite way. Red, green and blue are the primary colors for light. When two colored lights overlap, they produce lighter secondary colors, cyan, yellow or magenta. When all three are combined, they make white light. What is exciting here is that pigments and light share the same color wheel- it is only that the primary and secondary colors are reversed.

comparison of CYM and RGB color wheels

If you are using the traditional pigment primaries, red, yellow and blue, the relationship between additive and subtractive color wheels is confusing. Why would they share red and blue as primary colors but not the have one primary that is different (green or yellow)?


Unified Theory of Color — 2 Comments

  1. I like this, very simple and elegant, easy correlations. I know very little about art but I would imagine the three traditional pigment primaries arose because until modern pigments were invented, it was fairly hard to obtain natural cyan or magenta. The best people could do was blend varieties of blue and red with yellow. Of course, all of this rests heavily on the fact that human eyes have only three types of colour cell – if mantis shrimps were artists, I think this entire theory of three primary colours would fly out the window! Mantis shrimps have 16 colour receptors, which as a naturalist you probably already know. I really like this illustration: http://theoatmeal.com/comics/mantis_shrimp

    • Yes Gail, you are spot on. Especially with Magenta- we never had a good lightfast magenta until the Quinacridone pigments, a relatively recent discovery. I love your thoughts about the world as seen by a Mantis shrimp. Thank you.

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