Cite as:
Zaidi Q, Smithson H, 2004, "Roles for local adaptation and levels of reference in colour constancy" Perception 33 ECVP Abstract Supplement

Roles for local adaptation and levels of reference in colour constancy

Q Zaidi, H Smithson

By determining the locations of boundaries between colour categories, we measured changes in colour appearance as a function of the simulated illumination on a variegated background. Under prolonged adaptation to each illuminant, observers demonstrated a high degree of colour constancy. Using backgrounds that were chromatically biased, we tested whether this stability depends on the illuminant's cone-coordinates estimated from scene statistics. The chromatic bias of the background had little effect on the classification of test materials. We then (unknown to the observer) simulated conflicting illuminants on the test and on the background. Under these conditions, information about the background illuminant is provided by the spatial context, while information about the test illuminant is available only by collating local information over successive trials. Observers continued to demonstrate 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 presentations are critical in supporting colour constancy. In particular, we identify temporally extended but spatially local adaptation, and perceptual adjustments to levels of reference, as key determinants of the stability of colour appearance.

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