Color constancy and hue scaling.

In this study, we used a hue scaling technique to examine human color constancy performance in simulated three-dimensional scenes. These scenes contained objects of various shapes and materials and a matte test patch at the center of the scene. Hue scaling settings were made for test patches under five different illuminations. Results show that subjects had nearly stable hue scalings for a given test surface across different illuminants. In a control experiment, only the test surfaces that belonged to one illumination condition were presented, blocked in front of a black background. Surprisingly, the hue scalings of the subjects in the blocked control experiment were not simply determined by the color codes of the test surface. Rather, they depended on the sequence of previously presented test stimuli. In contrast, subjects' hue scalings in a second control experiment (with order of presentations randomized) were completely determined by the color codes of the test surface. Our results show that hue scaling is a useful technique to investigate color constancy in a more phenomenological sense. Furthermore, the results from the blocked control experiment underline the important role of slow chromatic adaptation for color constancy.