In the study of color perception, the first question that usually comes to mind is "what color is it?". In other words, we wish to develop a method of specifying a particular color which allows us to differentiate it from all other colors. It has been found that three quantities are needed to specify a particular color. For example, the relative amounts of red, green and blue in a color will serve to specify that color completely. This question was first approached by a number of researchers in the 1930's and their results were formalized in the specification of the CIE XYZ color space.
The second question we might ask, given two colors, is "how different are these two colors?" Just as the first question was answered by developing a color space in which three numbers specified a particular color, we are now asking effectively, how far apart these two colors are. This particular question was considered by researchers dating back to Helmholtz and Schrödinger, and David MacAdam provided... Read More