Document Detail

Color constancy in variegated scenes: role of low-level mechanisms in discounting illumination changes.
MedLine Citation:
PMID:  9316275     Owner:  NLM     Status:  MEDLINE    
For a visual system to possess color constancy across varying illumination, chromatic signals from a scene must remain constant at some neural stage. We found that photoreceptor and opponent-color signals from a large sample of natural and man-made objects under one kind of natural daylight were almost perfectly correlated with the signals from those objects under every other spectrally different phase of daylight. Consequently, in scenes consisting of many objects, the effect of illumination changes on specific color mechanisms can be simulated by shifting all chromaticities by an additive or multiplicative constant along a theoretical axis. When the effect of the illuminant change was restricted to specific color mechanisms, thresholds for detecting a change in the colors in a scene were significantly elevated in the presence of spatial variations along the same chromatic axis as the simulated chromaticity shift. In a variegated scene, correlations between spatially local chromatic signals across illuminants, and the desensitization caused by eye movements across spatial variations, help the visual system to attenuate the perceptual effects that are due to changes in illumination.
Q Zaidi; B Spehar; J DeBonet
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of the Optical Society of America. A, Optics, image science, and vision     Volume:  14     ISSN:  1084-7529     ISO Abbreviation:  J Opt Soc Am A Opt Image Sci Vis     Publication Date:  1997 Oct 
Date Detail:
Created Date:  1997-11-05     Completed Date:  1997-11-05     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  9800943     Medline TA:  J Opt Soc Am A Opt Image Sci Vis     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  2608-21     Citation Subset:  IM    
College of Optometry, State University of New York, New York 10010, USA.
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MeSH Terms
Color Perception / physiology*
Models, Biological*
Perceptual Masking / physiology
Sensory Thresholds
Space Perception / physiology
Grant Support

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