Color memory and color constancy

Abstract

Color constancy is the perceived stability of the color of objects despite changes in the light illuminating them. An object's color is considered constant if the current perceived color is judged to be in accord with the remembered one. Thus the accuracy and precision of color memory are fundamental to understanding this classic problem. Two hypotheses of color memory are tested here: (1) the photoreceptor hypothesis, which states that the color recalled from memory reproduces the light absorbed by each type of cone and (2) the surface-reflectance hypothesis, which states that the color recalled from memory is based on an inferred spectral reflectance of a surface that does not depend on the spectral distribution of the illuminant. In the experiments a test color is surrounded by either (i) a complex pattern composed of several colored patches or (ii) a uniform "gray" field at the chromaticity of the illuminant. In a control condition the test color is presented on a dark background. Long-term memory of the test color is measured in a production task begun 10 min after the end of the learning phase. In general, the results with a complex surround are consistent with the surface-reflectance hypothesis but not with the photoreceptor hypothesis. Color memory with the "gray" surround, on the other hand, shows a much stronger effect of the illuminant used during learning. These results are consistent with computational models of color constancy that require three or more chromaticities in view.

Bias effects of short- and long-term color memory for unique objects

“…A part of Jin and Shevell's color constancy study [11] using computer simulated Munsell patches in a simple geometric arrangement the authors also report than when there was no illuminant change between the learning and testing phase (i.e. a color memory task) participants matches deviated, for both durations tested, from the original color but the nature of this variation was not systematic.…”

Color constancy in the nearly natural image 2 Achromatic loci

“…Most studies of color constancy investigate the stability of object color appearance when the illumination is varied. [1][2][3][4]6,10,11,[13][14][15][16][17][18] Although this is a natural question, it neglects an important aspect of constancy, namely, whether object color appearance is stable when the other objects in the scene are varied. [19][20][21][22][23] Computational studies indicate that it is difficult to design a visual system that adjusts to changes of illumination without introducing a dependence of color appearance on the stimulus at multiple scene locations.…”

How does the cortex construct color?

“…An alternative view to Zeki et al's scheme may be to agree that V4 has a special role in constancy but to ask what is the relation between constancy and other factors such as memory and judgment. Some psychophysical studies of color constancy have shown convincingly that categorical color judgments (18) and color memory (19) are fundamental to color constancy and lesion studies support this view (6). Indeed it may not make sense to think of constancy as being separate from memory: the question ''is that the same color?''…”