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Lightness constancy: a direct test of the illumination-estimation hypothesis
1University of California, Santa Barbara, USA. mdrutherfo@hotmail.com
Psychological Science
|April 6, 2002
Summary
Color constancy models often assume illuminant estimation. This study tested that idea, finding that perceived lightness is not solely based on perceived illumination, challenging existing models.
Area of Science:
- Visual perception
- Color constancy
- Psychophysics
Background:
- Color constancy models commonly propose that the visual system estimates scene illuminants to determine object colors.
- A specific hypothesis links illuminant estimation to explicitly perceived illuminant.
Purpose of the Study:
- To test a version of the illumination-estimation hypothesis of color constancy.
- To investigate whether perceived lightness is dependent on perceived illuminant.
Main Methods:
- Two experiments involving appearance matching between chambers were conducted.
- Observers adjusted illumination and test patch properties to achieve matches.
- Perceived lightness and perceived illumination were assessed.
Main Results:
- Data contradicted the prediction that test patch luminances would be identical after matches.
- Manipulating a test patch's surround affected perceived lightness but not perceived illumination.
Conclusions:
- The illumination-estimation hypothesis, as formulated, is falsified by the experimental results.
- Perceived lightness is not solely determined by the perceived scene illuminant.
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