An angular interpretation of the CIE 1960 (u,υ) system is presented. This new development of the CIE 1964 (u,υ) (U*, V*, W*) system results in improved chromaticness-difference predictions and is more in accord with empirical constant-hue loci than the U*, V*, W* system.
G. T. YONEMURA, "Opponent-Color-Theory Treatment of the CIE 1960 (u,v) Diagram: Chromaticness Difference and Constant-Hue Loci," J. Opt. Soc. Am. 60, 1407-1409 (1970)