A color perceived by the human eye can be defined by a linear combination of the three primary colors red, green and blue. These three colors form the basis for the RGB-colorspace. Hence, each perceivable color can be defined by a vector in the three-dimensional colorspace. The intensity is given by the length of the vector, and the actual color by the two angles describing the orientation of the vector in the colorspace.
The RGB-space can also be transformed into other coordinate systems, which might be more useful for some applications. One common basis for the color space is IHS. In this coordinate system, a color is described by its intensity, hue (average wavelength) and saturation (the amount of white in the color). This color space makes it easier to directly derive the intensity and color of perceived light and is therefore more likely to be used by human beings.
©2003 R. Fisher, S. Perkins,
A. Walker and E. Wolfart.