Document Detail

Colour constancy in context: roles for local adaptation and levels of reference.
MedLine Citation:
PMID:  15493964     Owner:  NLM     Status:  MEDLINE    
By determining the locations of boundaries between colour categories, we measured changes in the colour appearance of test-reflectances as a function of the simulated illumination. Test-reflectances were displayed against a variegated background of reflectance samples. Under prolonged adaptation to each illuminant, observers demonstrated a high degree of appearance-based colour constancy. By using backgrounds that consisted of chromatically biased sets of reflectances, we tested whether this stability depends on estimates of the illuminant's cone-coordinates based on simple scene statistics. The chromatic bias of the background had only a small effect on the classification of test materials. To compare the roles of spatially local and spatially extended estimation processes, we then (unknown to the observer) simulated different illuminants on the test and on the background. Observers continued to demonstrate reasonable colour constancy. To examine the relative roles of automatic adaptation and perceptual strategies, we reduced the duration of exposure to the test compared to exposure to the background (under the conflicting illuminant). The results suggest that mechanisms that preserve information across successive test-presentations (e.g. spatially local adaptation with a time course of a few seconds, and perceptual adjustments to levels of reference) are key determinants of the stability of colour appearance.
Hannah Smithson; Qasim Zaidi
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.     Date:  2004-08-26
Journal Detail:
Title:  Journal of vision     Volume:  4     ISSN:  1534-7362     ISO Abbreviation:  J Vis     Publication Date:  2004 Aug 
Date Detail:
Created Date:  2004-10-20     Completed Date:  2004-12-16     Revised Date:  2008-04-29    
Medline Journal Info:
Nlm Unique ID:  101147197     Medline TA:  J Vis     Country:  United States    
Other Details:
Languages:  eng     Pagination:  693-710     Citation Subset:  IM    
Institute of Ophthalmology, University College London, London, UK.
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MeSH Terms
Adaptation, Ocular / physiology*
Color Perception / physiology*
Reference Standards
Space Perception / physiology
Grant Support

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

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