17 July 1998 Visual search and natural color distributions
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Abstract
We examined visual search for color within the distributions of colors that characterize natural images, by using a foraging task designed to mimic the problem of finding a fruit among foliage. Color distributions were taken from spectroradiometric measurements of outdoor scenes and used to define the colors of a dense background of ellipses. Search times were measured for locating test colors presented as a superposed circular target. Reaction times varied from high values for target colors within the distribution (where they are limited by serial search based on form) to asymptotically low values for colors far removed from the distribution (where targets pop out). The variation in reaction time follows the distribution of background contrasts but is substantially broader. In further experiments we assessed the color organization underlying visual search, and how search is influenced by contrast adaptation to the colors of the background. Asymmetries between blue-yellow and red-green backgrounds suggest that search times do not depend on the separable L-M and S- (L+M) dimensions of early postreceptoral color vision. Prior adaptation facilitates search over adaptation to a uniform background, while adaptation to an inappropriate background impedes search. Contrast adaptation may therefore enhance the salience of novel stimuli by partially discounting the ambient background.
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Michael A. Webster, Michael A. Webster, Vincent E. Raker, Vincent E. Raker, Gokhan Malkoc, Gokhan Malkoc, } "Visual search and natural color distributions", Proc. SPIE 3299, Human Vision and Electronic Imaging III, (17 July 1998); doi: 10.1117/12.320142; https://doi.org/10.1117/12.320142
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