Color-Difference Matches

Abstract

For a given pair of colors (i) and (j) of the same brightness, an observer generates in a visual colorimeter a third color (i,j) such that he perceives all three colors to be equally bright and the three differences between them to be of equal size. In color-perception space, the three colors form an equilateral triangle on a surface of constant brightness. The precision of setting the third color (i,j) can be characterized by ellipsoids in color space. Three observers take part in the experiment and over 30 pairs of colors (i) and (j) are presented to them. In approximately 50% of the cases a given observer will agree, within the uncertainty of his own data, with the mean color (i,j) of another observer. The corresponding color-difference-matching ellipses (cross sections of the ellipsoids) of the different observers show a satisfactory correlation. The experimental data presented may be used to test color-difference formulas and the chromaticity spacing in UCS diagrams.