Color mixing

White light split by a prism. The additive primary colors are clearly visible.

There are two types of color mixing: Additive and Subtractive. In both cases there are three primary colors, three secondary colors (colors made from 2 of the three primary colors in equal amounts), and one tertiary color made from all three primary colors.

A simulated example of additive color mixing

Additive Mixing

Additive mixing of colors generally involves mixing colors of light. In additive mixing of colors there are three primary colors: red, green, and blue. In the absence of color or, when no colors are showing, the result is black. If all three primary colors are showing, the result is white. When red and green combine, the result is yellow. When red and blue combine, the result is magenta. Additive mixing is used in television and computer monitors to produce a wide range of colors using only three primary colors.

A simulated example of subtractive color mixing

Subtractive Mixing

Subtractive mixing is done by selectively removing certain colors, for instance with optical filters. The three primary colors in subtractive mixing are yellow, magenta, and cyan. In subtractive mixing of color, the absence of color is white and the presence of all three primary colors is black. In subtractive mixing of colors, the secondary colors are the same as the primary colors from additive mixing, and vice versa. Subtractive mixing is used to create a variety of colors when printing on paper by combining a small number of ink colors, and also when painting. The mixing of pigments does not produce perfect subtractive color mixing because some light from the subtracted color is still being reflected. This results in a darker and desaturated color compared to the color that would be achieved with ideal filters.

Importance to vision

To most people, red and green yielding yellow and orange, or blue and yellow producing white, seems strange, as opposed to the "normal" blue plus yellow giving black. In this case one must understand that color mixing in the retina is a subtractive process, rather than the additive process of shining a mix of colors against a white surface. For example, a blue pigment is seen from the outside because it reflects blue and some green, a yellow pigment is yellow because it reflects yellow and some green, and absorbs red and blue. When white light falls on a combination of blue and yellow, all wavelengths are absorbed except for green.^[1]

See also

• Color theory
• Subtractive color
• Additive color

References

• Macaulay, David and Neil Ardley (1988). The New Way Things Work. London: Dorling Kindersley Ltd. ISBN 0395938473.