Color Appearance Changes Resulting from Iso-luminant Chromatic Adaptation

By means of asymmetric color matching, the effects of steady-state chromatic adaptation on the color appearance of briefly presented chromatic flashes were investigated. The adapting and test lights were of equal luminance (35 cd/m2) and differed from the standard grey adapting light either along the L-2M (red and green), or along the S-(L+M) (yellow and violet) line. The red (green) adapting light results in 6% positive (negative) L cone contrast and 11% negative (positive) M cone contrast with respect to the grey adapting light. The violet (yellowish) adapting light yields a positive (negative) S cone contrast of 50% relative to the standard adapting light. The main findings are: (i) iso-luminant adapting lights that differ only in their L-2M signal (red and green) resulted in asymmetric matches that differ mainly in the L-2M coordinate; (ii) iso-luminant adapting lights that differ in their S cone excitation only (yellow and violet) result in asymmetric matches that differ mainly in their S cone coordinate; (iii) the largest difference between test and match coordinates is found in the S cone signal for violet adaptation; (iv) the luminance differences of the asymmetric matches are within 1% of the mean luminance and are mostly non-systematic; (v) adaptation to iso-luminant red and green lights yields adaptational changes mainly in the L cones and not in the M cones; (vi) substantial quantitative deviations from a von Kries law are observed for L cone signals for red and green adaptation and for S cone decrements under yellow adaptation; (vii) S cone-isolating adapting lights results in small additive shifts in the S cone matches; adapting lights differing only in the L and M cone signal from the standard grey adapting light yield additive shifts only in the L and M cone matches.