The Muser
Physics & Physiology of Color
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The Muser |
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The Color Musings Return to |
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There are two ways to mix colors. If we mix light, we call it additive mixture. When we mix inks, dyes or pigments, that is subtractive mixture. There is really no difference in the way the colors behave in the two circumstances. Only the mechanics of the processes are different. Additive color mixture begins with the absence of light (black), and adds colors of light together to form new colors. The illustration shows how this kind of mixture might be done with three slide projectors. Red, green and blue are typically used as the additive primary colors. In pairs, they combine to create cyan, magenta and yellow. When all three of the additive primary colors are added together, in approximately equal intensities, they produce white light. Additive mixture is used in theatrical lighting, and in computer monitors and TV screens. (Examine your computer screen or TV with a very strong magnifying lens, and you'll see that the image consists of a matrix of red, green, and blue dots, or pixels.) How does this additive mixture work? It's no mystery really, and it has little or nothing to do with the physiology of our eyes or brain. This is simple math.
Where two colors overlap, or are added together, their combined light accounts for two-thirds of the spectrum. (1/3 + 1/3 = 2/3) Those combinations always produce the colors cyan, magenta, and yellow. Where all three colors overlap, the entire spectrum is present, so we see white light. It's that simple. This demonstration of additive color mixture lays the foundation to the understanding complementary colors, subtractive color mixture, and primary colors. What are complementary colors? What are primary colors? Can color mixtures be predicted? © J. C. Adamson, 2001 |
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The red color we use for additive color mixture is composed of the light from one-third of the spectrum. The green color is another third of the spectrum. And the blue color is the remaining third.