The use of uniform chromaticity scales

The C.I.E. trichromatic system is capable of modification to a similar system of three coordinates in which a diagram of colours has the property that the distance between the points representing two colours is approximately proportional to the subjective colour-difference. It is shown that a similar effect can be obtained by a distortion of the C.I.E. coordinate lattice giving either the Uniform Chromaticity System proposed by Judd or the Rectangular Uniform Chromaticity System proposed by Breckenridge and Schaub. Nomographic transformations between the systems are also described. The object of these transformations is to enable results which are recorded on the C.I.E. basis to be plotted or visualized on the U.C.S. system.