Skew hypothesis for surface gloss perception revisited by the adaptation paradigm S Nakauchi, R Nishijima, Y Tani, K Koida, M Kitazaki, T Nagai |
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Department of Computer Science and Engineering, Toyohashi University of Technology, Japan
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| This study performed adaptation experiments to measure the gloss aftereffect. We had subjects adapt to two images presented side by side (one of them was identical as a control) with fixating at a position between them. Following 40 s initial adaptation, two glossy surfaces were presented, and we asked subjects to judge which side of the display appeared glossier to determine the gloss aftereffects from the PSE shifts. Exp.1 used following adopters; Spec, glossy surface; Mat+, mat surface; Mat-, negative of Mat+; Rot+, mat surface with rotated specular highlights; Rot-, negative of Rot+. All the adaptors had the same value of mean luminance and RMS contrast. The histogram skew of Spec, Mat+ and Rot+ was adjusted to +0.6, and to -0.6 for Mat- and Rot-. Gloss aftereffects were obtained only for Spec, Rot+ and Rot-, and it seems that the sub-band contrasts of adaptors mainly play a role. Exp.2 investigated the skew adaptation (difference of the gloss aftereffects between positive and negative skewed adaptors) using the filtered white noise images with various cut-off frequencies. As a result, the skew adaptation was observed with clear bell-shaped frequency dependency, implying the adaptable skew processing probably at relatively early visual stages. |
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