SUPRATHRESHOLD COLOR-DIFFERENCE ELLIPSOIDS FOR SURFACE COLORS

The RIT-DuPont visual color-difference data [Color Res. Appl. 16, 297- 316 (1991)] have been used to estimate contours of equal color-differe nces (ellipsoids) at 19 color centers, in CIELAB and x, y, Y/100 color spaces. The ellipsoid fits are better in the CIELAB space than in x, y, Y/100, since the design of the RIT-DuPont experiment emphasized dir ectional balance in CIELAB. The ellipsoids estimated are hardly tilted with respect to L to Y/100, and they appear to be in overall good ag reement with those reported for object colors in recent publications. From the characteristics and accuracy of the RIT-DuPont experiment, th e current ellipsoids can be considered highly reliable and representat ive of color discrimination under the observational conditions employe d, these closely following the ''reference conditions'' recently sugge sted by the CIE for industrial color-difference evaluation [Color Res. Appl. 20, 399-403 (1995)]. (C) 1997 John Wiley & Sons, Inc.