Effect of a yellow filter on brightness evaluated by asymmetric matching: measurements and predictions

Abstract

We found that yellow filters reduce the mean brightness of a set of coloured samples significantly less with blue surrounds than with black, achromatic or yellow ones, in comparison with the naked eye and less than a yellow surround in comparison with a luminance-matched grey filter. The predictions of Hunt's model and Guth's ATD95 agree with these results. The yellow filter is actually capable of significantly increasing the brightness with the blue surround both in comparison with the naked eye (although only for our younger observer) and with the neutral filter. We show that in some samples the yellow filter causes global response increments in the chromatic mechanisms that compensate the response reduction in the achromatic mechanism, resulting in increased brightness. Although global chromatic response increments may arise from any chromatic mechanism, the blue–yellow mechanism determines in most cases the final result, even when the response of the red–green mechanism decreases.