Estimation of color-difference formulae at color discrimination threshold using CRT-generated stimuli

The advanced color-difference formulae, CMC, CIE94, and the recently propos ed CIEDE2000 formula, together with the basic CIELAB system, were estimated using the chromaticity discrimination threshold data at CIE Gray and Blue color centers. Gray is the most basic color and blue is, perceptually, in t he most different region from other areas across the color space. The test stimuli, evenly distributed in the (a*, b*)-, (a*, L*)-, and (b*, L*)-plane of the CLELAB space, were generated on a CRT display, driven by a VSG syst em. Each direction from each color center was assessed 3 times by a panel o f 9 normal color-vision observers with the psychophysical method of interle aved staircase. The experimental data were reliable and consistent with oth er studies according to the observer accuracy and fitted ellipse parameters . A comprehensive analysis shows the color discrimination tolerances could be well fitted by ellipses, and the CIEDE2000 and CIELAB formulae performed better than CIE94 while the CMC worst at the threshold level for the color centers studied.