Parametric effects on surface color‐difference evaluation at threshold

Experiments on thresholds of perceptible color‐difference at CIE color centers have been extended for the parametric effects of the lightness of an achromatic surround and of a separating gap between a pair of painted specimens. Components of perceived color‐difference (hue, chroma, lightness) approximately could be assigned to geometric elements of threshold ellipsoids and used for component analysis. A study of ellipsoid and city‐block modelling revealed ellipsoid to be slightly better. An increase of total threshold by changed lightness of the achromatic surround was found only in the case of the dark CIE Blue, but in every case a gap increased threshold the darker the CIE color center. The results can be used for a correction in color‐difference evaluation.