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James Schirillo, Genevieve Heckman, Thomas Barra; A chromatic test of shadow compatibility and equal cone excitation ratios. Journal of Vision 2003;3(9):446. doi: https://doi.org/10.1167/3.9.446.
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Three chromatic versions of Adelson's (1993) wall of blocks stimuli were made either shadow compatible or shadow incompatible to test Logvinenko's (2001) hypothesis that shadow compatibility is required to generate the perception of shadows and concomitant lightness illusion. Stimuli consisted of CRT simulations of Munsell gray surfaces under 2854 deg. K (yellow) to 20,000 deg. K (blue) illuminants. The three sets were (1) either all yellow or all blue surfaces that varied only in lightness (i.e., a monochromatic version of Logvinenko's achromatic stimuli), (2) alternating regions of yellow and blue surfaces, (i.e., to appear like adjacent chromatic neutral density filters when shadow compatible), and (3) surfaces of different yellows and blues that varied only in chromaticity (i.e., a chromatic transformation of Logvinenko's stimuli). An additional condition altered the surface colors slightly to equate cone excitation ratios across the shadow borders, which Foster & Nascimento (1994) claim can enhance color constancy. Observers varied the hue, saturation and chromaticity of cube tops in one ‘transparent’ region to match the cube tops in another. Arranging surfaces to be shadow compatible created the expected Adelson-Logvinenko illusion in all stimulus sets. Interestingly, the cube tops within either the all yellow or all blue dark shadowed regions (set 1) appeared both lighter and bluer. Only when the stimuli contained both chromatic and luminance shadow borders (set 2) were equal cone excitation ratios effective, suggesting that a purely chromatic shadow (set 3) is not enhanced by equating cone excitation ratios.
Adelson(1993). Perceptual organization and the judgment of brightness.Science, 262, 2042–2044, FosterNascimento(1994). Relational color constancy from invariant cone-excitation ratios, Proc. R. Soc. London Ser. B., 257, 115–121, Logvinenko(2002). Articulation in the context of edge classification. Perception, 31(2), 201–207.
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