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X Xian, SK Shevell; Chromatic Induction from Complex Surrounding Patterns . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3986.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Chromatic contrast and assimilation are two aspects of chromatic induction. Here, we used inducing patterns composed of two chromaticities so that assimilation and contrast may cause hue shifts in the same direction. These patterns induce large change in color appearance. The present study examines the influence of test-field luminance on these hue shifts in order to test alternative explanations of chromatic induction. Methods: A round test field, presented on a CRT, was composed of a test surround (4.3 degree diameter) and a test ring (1.74 - 2.06 degree inner-outer diameter). Different configurations of the test surround were obtained by changing the chromaticities of concentric rings that compose it. A separate comparison field was formed by a uniform EEW surround and a comparison ring. The luminance of both surrounds was at 15cd/m2. The observer's task was to adjust the comparison ring to match the appearance of the test ring, whose luminance in different conditions was at 13cd/m2, 15cd/m2 or 20cd/m2. Results: Induction from surrounds composed of alternating concentric inducing rings at two different chromaticities caused a larger shift in color appearance than a uniform surround at either of the two component chromaticities. Removing light from a uniform surround that is not contiguous with the test ring shifted the matches in the direction of chromatic assimilation. Replacing that non-contiguous light with a different chromaticity shifted the matches in the direction of chromatic contrast from the added chromaticity. There was no systematic shift in appearance with the luminance of the test ring. Conclusion: Chromatic induction cannot be explained solely by non-neural factors or complete neural spatial integration. A theory proposed to account for these results combines chromatic contrast from a large surrounding area and assimilation from a more local region.
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