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Ali Yoonessi, Frederick Kingdom; Is color patchy?. Journal of Vision 2008;8(6):340. doi: https://doi.org/10.1167/8.6.340.
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© ARVO (1962-2015); The Authors (2016-present)
In many natural scenes shadows and shading, which are primarily luminance-defined features, proliferate. Hence one might expect that the chromatic layers of natural scenes, which more faithfully represent the layout of object surfaces, will contain relatively fewer and larger uniform regions than the luminance layers, i.e. will be more ‘patchy’. This idea was tested using images of natural scenes that were decomposed into chromatic and luminance layers modeled as the ‘red-green’, ‘blue-yellow’ and ‘luminanc’ channel responses of the human visual system. Patchiness was defined as the portion of pixels falling within a threshold in the band-pass filtered image, averaged across multiple filter scales. The red-green layers were found to be the most patchy, followed by the blue-yellow layers, with the luminance layers being the least patchy. The correlation of patchiness with the slope of the Fourier amplitude spectrum revealed a medium-sized negative correlation for the red-green layers (−0.48), and weaker negative correlations for the luminance and blue-yellow layers. We conclude that the chromatic layers of natural scenes contain larger uniform areas than the luminance layers, and that this is not predicted by the slope of the Fourier amplitude spectrum.
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