Influence of rods on hue scaling of surface color

Abstract

Rods produce a variety of different effects on hue perception at dim light levels that stimulate both rod and cone photoreceptors. Current understanding of these effects is primarily based on research comparing color appearance of spectral lights across adaptation conditions that either maximize (dark-adapted) or minimize (cone plateau) the contribution of rod signals to vision (Buck, 2004). In this study, we ask whether the types of rod influence previously reported for lights generalize to colored surfaces during free viewing. Observers used a hue scaling procedure (Gordon, Abramov, & Chan, 1994) to judge the color appearance of sixty Munsell color chips selected from the Munsell 4-, 6-, and 8-value planes with luminance ranging from 4 to 0.01 cd m^-2. For each plane, rod influence was measured by comparing hue judgments made after dark adaptation with those made during the cone plateau. At mesopic light levels, our results are qualitatively consistent with previous studies showing effects on green and blue hue sensations. A significant rod influence was found for some, but not all, colors represented by the Munsell hue circle. The largest rod influence was observed for green hue sensations with a green hue bias for chips 5YR to 10GY. A smaller blue hue bias was observed for 5G to 5B and no rod influence was observed between 10B to 10R. Our results suggest that during natural viewing the influence of rods on surface color appearance is to primarily affect green, and to a lesser extent, blue hue sensations.

Acknowledgments

This research is supported by Grant-in-Aid for Challenging Exploratory Research of Japan Society for the Promotion of Science No.22650054.