Abstract
Some studies have shown that spatial structure of the scene affects lightness perception. However, most of them focus on the context of the surrounding luminance presented explicitly in the scene. This study investigated whether lightness perception is influenced by the spatial structure with no explicit information of luminance. In addition, we measured the illumination and the volume of space in actual scenes to examine whether the size of space in our environment was related to the illumination in the space. We used the stimulus consisted of the random-dots with 3D structure defined by binocular disparity. Since the density of dots was kept uniform over the stimulus, the influence of luminance and texture should be eliminated. Observers matched the lightness of a test patch presented in the stimulus space to that of a comparison patch presented in isolation by adjusting the comparison patch luminance. In experiment 1, we changed the angle of the ceiling of the stimulus space above the test patch to intend manipulating magnitude of illumination based on the light-from-above assumption. In experiment 2, we changed the width of the stimulus space to test whether observed positive correlation between the illumination and the volume of space in actual scenes was used for lightness perception. Results showed that matched luminance significantly increased when the space was opened and the width of space was increased, in other words, when the test patch was interpreted to receive weak illumination. These results suggest that the visual system could refer implicit information of the illumination of the scene from spatial structure for lightness perception.
Meeting abstract presented at VSS 2014