Document Detail

Color constancy in natural scenes explained by global image statistics.
MedLine Citation:
PMID:  16961965     Owner:  NLM     Status:  MEDLINE    
To what extent do observers' judgments of surface color with natural scenes depend on global image statistics? To address this question, a psychophysical experiment was performed in which images of natural scenes under two successive daylights were presented on a computer-controlled high-resolution color monitor. Observers reported whether there was a change in reflectance of a test surface in the scene. The scenes were obtained with a hyperspectral imaging system and included variously trees, shrubs, grasses, ferns, flowers, rocks, and buildings. Discrimination performance, quantified on a scale of 0 to 1 with a color-constancy index, varied from 0.69 to 0.97 over 21 scenes and two illuminant changes, from a correlated color temperature of 25,000 K to 6700 K and from 4000 K to 6700 K. The best account of these effects was provided by receptor-based rather than colorimetric properties of the images. Thus, in a linear regression, 43% of the variance in constancy index was explained by the log of the mean relative deviation in spatial cone-excitation ratios evaluated globally across the two images of a scene. A further 20% was explained by including the mean chroma of the first image and its difference from that of the second image and a further 7% by the mean difference in hue. Together, all four global color properties accounted for 70% of the variance and provided a good fit to the effects of scene and of illuminant change on color constancy, and, additionally, of changing test-surface position. By contrast, a spatial-frequency analysis of the images showed that the gradient of the luminance amplitude spectrum accounted for only 5% of the variance.
David H Foster; Kinjiro Amano; Sérgio M C Nascimento
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Visual neuroscience     Volume:  23     ISSN:  0952-5238     ISO Abbreviation:  Vis. Neurosci.     Publication Date:    2006 May-Aug
Date Detail:
Created Date:  2006-09-11     Completed Date:  2006-10-18     Revised Date:  2013-03-12    
Medline Journal Info:
Nlm Unique ID:  8809466     Medline TA:  Vis Neurosci     Country:  England    
Other Details:
Languages:  eng     Pagination:  341-9     Citation Subset:  IM    
Sensing, Imaging, and Signal Processing Group, School of Electrical and Electronic Engineering, University of Manchester, Manchester, United Kingdom.
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MeSH Terms
Color Perception / physiology*
Computer-Aided Design
Contrast Sensitivity / physiology*
Discrimination (Psychology) / physiology
Pattern Recognition, Visual / physiology
Photic Stimulation / methods
Psychophysics / methods
Space Perception / physiology
Grant Support
064669//Wellcome Trust

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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