Abstract
It has been suggested that the mode of color appearance is determined not solely by physical properties of the stimulus, but by the conditions of surrounding stimuli. Coplanar hypothesis suggests that the information provided in the same plane plays an important role for the judgment of the lightness. We measured the upper-limit luminances of the test stimulus for the surface-color mode in a three-dimensionally represented environment to study the effects of depth and luminance conditions on the mode perception. Stimulus was displayed on a CRT monitor. Subjects fused two images with disparity to perceive a three-dimensional scene. We simulated a room environment whose walls had a luminance gradient along the depth. A test stimulus and two array-type surrounding stimuli composed of 10 different colors were presented in the different depth. The luminances of the surrounding stimuli were changed. The test stimulus was presented in three different depths: the same depth as one of the surroundings and the intermediate depth. Subjects set the luminance of the test color to the point where it just ceased to appear in the complete surface-color mode. The upper-limit luminances of the test colors changed as the luminances of the surrounding stimulus displayed in the same depth. We obtained the same trends when the test stimulus was displayed spatially separated from surroundings. Our results indicate that the perception of the surface-color mode is mainly affected by the condition of the stimulus displayed in the same depth. These results support that the belongingness — to which group in the environment the stimulus belongs — is important, and that the mode of color appearance is determined coplanar in a three-dimensional environment, taking the depth information into consideration.