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RGB Color Values

A typical way to determine the color for a point, or pixel, on the computer screen is to give values for the three primary colors Red, Green and Blue. Note that these are primaries in an additive color scheme: unlike in painting, when combining colored lights, red and green make yellow.

In a so-called 24-bit color display, one can choose any value from 0 to 255 to determine the amount of Red, Green and Blue in a color. Thus there are 256x256x256 possible colors, for a total of 16,777,216 possible colors. The numbers that determine colors in this way are called RGB values.

This way of assigning colors affected the choices we made in designing the color wheel. Because Red, Green and Blue are the additive primaries, we spaced them equally around the circle. We put an RBG triple of (255,0,0) where we wanted to see pure red and (255,255,0) halfway between Red and Green on the unit circle. From there it was a matter of interpolation.

We think that there is no single universal correct way to make a color wheel; after all it is a human artifact more than a scientific object rooted in physics. Since our original work, we have redesigned the color wheel using HSV values, a different way of determining color by Hue, Saturation and Value, but that is another story.

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Communications in Visual Mathematics, vol 1, no 1, August 1998.
Copyright © 1998, The Mathematical Association of America. All rights reserved.
Created: 19 Aug 1998 --- Last modified: 18 Aug 1998 23:59:59
Comments to: CVM@maa.org