COLOR CONSTANCY UNDER NATURAL AND ARTIFICIAL ILLUMINATION

Color constancy was studied under conditions simulating either natural or extremely artificial illumination, Four test illuminants were used : two broadband phases of daylight (correlated color temperatures 4000 and 25,000 K) and two spectrally impoverished metamers of these light s, each consisting of only two wavelengths, A computer controlled colo r monitor was used for reproducing the chromaticities and luminances o f an array of Munsell color samples rendered under these illuminants, An asymmetric haploscopic matching paradigm was used in which the same stimulus pattern, either illuminated by one of the test illuminants, or by a standard broadband daylight (D-65), was alternately presented to the left and right eye, Subjects adjusted the RGB settings of the s amples seen under D-65 (match condition), to match the appearance of t he color samples seen under the test illuminant, The results show the expected failure of color constancy under two-wavelengths illumination , and approximate color constancy under natural illumination, Quantita tive predictions of the results were made on the basis of two differen t models, a computational model for recovering surface reflectance, an d a model that assumes the color response to be determined by cone-spe cific contrast and absolute level of stimulation (Lucassen & Walraven, 1993), The latter model was found to provide somewhat more accurate p redictions, under all illuminant conditions. Copyright (C) 1996 Elsevi er Science Ltd.