Abstract

We studied the spatial and temporal characteristics of chromatic adaptation to lights resembling natural illuminants, by measuring how adaptation to these lights affected observers' setting of a test light to be achromatic. We used a color CRT display system to present test patches and background lights in different spatial and temporal configurations. To measure the spatial characteristics of adaptation the test patch was viewed against an incandescent background (CIE illuminant A) of variable size enclosed by a daylight surrounding region (CIE illuminant D65) of fixed outside dimensions. By varying the size of the tungsten background we could assess the effect of the daylight region on the appearance of the test patch. To study the temporal characteristics of adaptation we used a similar arrangement, except that we temporally alternated the tungsten and daylight regions, and varied the time for which the tungsten background was visible. Our results show that the mechanisms of chromatic adaptation are spatially localized and have a time constant of the order of 10 s. This time-constant may be long enough to permit normal eye-movements over a scene to leave the visual system adapted to the space-average chromaticity.

© 1990 Optical Society of America