Abstract

The original color triangle of Maxwell (1855) is designed to show linear color mixture relations. A well-known extension of the color triangle makes reference to fundamental primaries and thereby serves as a cone excitation diagram. Here, a further extension is presented showing the characteristic features of linear dichromatic and trichromatic opponent–color vision. Its constituent elements are 3 straight lines along which one of the perceptual criteria "no blue-yellow chroma" "no green-red chroma" or "no brightness" holds. These loci are the intersections of two-dimensional subspaces of the color space with the plane of the color triangle. Such an opponent–color triangle may be superimposed on a cone excitation diagram. Together, they show the (projective) core of a linear physiological color theory, of which one important feature is the direct decomposition of a color into chrominance and luminance.

© 1992 Optical Society of America