Shoji SUNAGA,¹ Satoshi SHIOIRI,² Hirohisa YAGUCHI² and Souichi KUBO²

¹Graduate School of Science and Technology, Chiba University, ²Department of Image Science, Chiba University, 1-33, Yayoi, Inage-ku, Chiba, 263 Japan

(Accepted November 25, 1994)

We examined 1) whether the perception of shape from shading is based on luminance or brightness by testing the additivity law, and 2) whether the spatial frequency contents in the stimulus affect on the spectral sensitivity. We measured the relative radiance at which shading disappeared in a simple shading figure. Results showed that 1) the additivity law holds for shading disappearance settings and that 2) the sensitivity for green to white decreased as higher spatial frequencies in the figure decreases. These results suggest that the perception of shape from shading is based on a luminance type additive mechanism and that the spectral sensitivity of the mechanism varies depending on spatial frequency.

Key words : perception of shape from shading, form perception, luminance, brightness, luminance additivity, spatial frequency, spectral sensitivity