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Laysa Hedjar, Arthur Shapiro; Separate color systems for different spatial scales. Journal of Vision 2018;18(10):587. doi: 10.1167/18.10.587.
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Color constancy is often ascribed to higher-level perceptual inferences that allow the visual system to discount the illumination to estimate the reflectance of a material. However, our laboratory has suggested that much of what is required for color constancy is available in the spatial structure of the stimulus: chromatic content in the low spatial frequency (LSF) range corresponds roughly to the global illumination; chromatic content in the high spatial frequency (HSF) range remains roughly invariant to illumination changes. Here we examine the extent to which independent changes in the color of HSF and LSF content produce perceptual analogs of reflectance and illumination. Images were decomposed into spatial-band component images. The hue of the decomposed images were shifted in L*a*b* space (see Nascimento et al., 2017) and then images were recombined. Objects or shapes from the images were extracted and isolated on a gray background. Participants were asked to 1) match the isolated object to the same object within the manipulated image; 2) match the isolated object to the object isolated directly from the manipulated image on a gray background; and 3) adjust the hue of a white paper to appear as though it were under the same illumination as in the manipulated image. Results are plotted as a function of hue shift produced at each spatial band. Demonstrations produced from the images suggest that object color corresponds to HSF color and illumination corresponds to LSF color. More than that, swapping LSF content between images creates the impression of a change in illumination but not a change in object color, whereas swapping HSF content between images creates the impression of a change in object color but not in illumination. We speculate about the locus and function of the separation and recombination of distinct HSF and LSF color vision systems.
Meeting abstract presented at VSS 2018
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