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 three 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 2-D 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.

© 1988 Optical Society of America