COLOR-DISCRIMINATION THRESHOLDS TRANSLATED FROM THE CIE (X,Y,Y) SPACETO THE CIE 1976 (L(ASTERISK),A(ASTERISK),B(ASTERISK))

Departures from exact ellipticity when color-discrimination ellipsoids or ellipses are translated to CIELAB have been numerically analyzed. The greatest distortions for ellipses were around 5% at the most satur ated orange-red centers. The distortions for ellipsoids were of the sa me order as those of the ellipses at the five CIE centers. These small distortions are well covered by the interobserver variability and cou ld be ignored in most cases, but an appropriate method must be used fo r the translation of color-threshold results to CIELAB. Experimental r esults published by Luo and Rigg for 132 chromaticity-discrimination e llipses are expressed in CIELAB. These results may be useful in checki ng the performance of new color-difference formulas. (C) 1994 John Wil ey and Sons, Inc.