CHROMATICITY DISCRIMINATION THRESHOLDS WITH APERTURE AND OBJECT COLORS - EXPERIMENTAL RESULTS AND PREDICTIONS OF SOME RECENT COLOR-DIFFERENCE FORMULAS

Threshold-discrimination ellipses were obtained by three normal observ ers, at five color centers, by the use of two experimental devices, wh ich provided light-surface colors, and the same method and experimenta l conditions. The ellipses obtained for each center in both devices we re quite similar when the sample distributions were appropriate and sl ightly smaller for object color than for aperture color. The ellipses predicted by three recent color-difference formulas based on the CIE u niform color space (CIELAB) were compared with those experimentally ob tained by us as well as by other researchers who analyzed a greater nu mber of color centers. The color-difference formula proposed by the CI E Technical Committee 1-29 [Color Res. Appl. 18, 137 (1993)] provides the best prediction of the semiaxis relationship for all the experimen tal datasets used, confirming their good performance in previous works [Appl. Opt. 33, 8069 (1993)], although the differences with respect t o the experimental results are higher than those attributable to the i nterobserver variability. (C) 1996 Optical Society of America