The fry uniform chromaticity scale diagram

AbstractIn 1945 I created a uniform chromaticity diagram which was a modification of the 1931 CIE Chromaticity Diagram. At that time I tried to relate it to a modulation theory of color vision which has proved to be untenable. In 1965 I switched to a zone theory of color vision which provides a more acceptable physiological basis for my UCS diagram. In the present article I want to explain how the two are related. I make use of three diagrams. The first (my uv diagram) is a color mixture diagram which deals with responses of the cones. The second (my un vn diagram) deals with the yellow‐blue and red‐cyan signals generated in two separate sets of fibers of the optic nerve. It is this independence which permits the relation between u″ and u on the one hand and between v″ and v on the other to be nonlinear. This is my UCS diagram. It yields better uniformity of discrimination steps across the diagram than is possible with a projective diagram. The second diagram is designed to deal with discrimination at the threshold level. The third diagram (my m n diagram) deals with the suprathreshold spacing of the Munsell colors. It is produced by scissoring the two sets of coordinate lines of the u″ v″ diagram around the standard stimulus C. This is related to the way in which signals in the two sets of fibers mix to produce intermediate colors.