Fig. 1.

A, Illustration of the color constancy display under the neutral illuminant C (daylight). Each of the Mondrian patterns consisted of a random arrangement of small, colored rectangles and a central larger, horizontal gray rectangle.B, Same reflectances under a bluish simulated illuminant. The colored patches above the Mondrian illustrate settings at different levels of color constancy (not shown during the experiment). C, CIE coordinates of the simulated surface colors of 226 different Munsell chips illuminated by five different illuminants. The corresponding transformation in color space for each Munsell chip under the four colored illuminants is indicated by the appropriate color; the neutral setting under CIE standard illuminant C is indicated in black.D, The observer had to adjust the color of the central rectangle by changing its color value along one of the cardinal directions of color space, as illustrated by the colored lines, until it appeared as a neutral gray under each of the five illuminants.