Abstract
Previous studies have reported that chromaticity information in object images enhances perceived translucency. The aim of this study, was to elucidate how color forms image features that contribute to translucency in psychophysical experiments. The stimuli were computer-graphics images of translucent objects with different spectral scattering coefficients (i.e., hues) and various optical and geometrical parameters. Achromatic images with the same luminance as the chromatic images were also created. Perceived translucency was measured using Thurston’s pairwise comparison, and the effect of chromaticity or translucency was evaluated by comparing translucency in achromatic and chromatic images. The results showed higher perceived translucency for the chromatic object images than the achromatic ones. Subsequently, we analyzed how different image features correlate with the effects of color on translucency using multiple regression analysis. The result indicated that the luminance- chromaticity correlation, which has been proposed as a potential cue for translucency could hardly explain the color effects. Rather, we found that the change in brightness contrast in the diffuse components modulated by the Helmholtz–Kohlrausch (H-K) effect was strongly and negatively correlated with the color effects. These results suggest that some image features, which covary with brightness contrast brightness contrast, contribute to the color effects on translucency.