Specular highlights improve colour constancy when other cues are weakened

Wedge-Roberts, Rebecca; Aston, Stacey; Beierholm, Ulrik; Kentridge, Robert; Hurlbert, Anya; Nardini, Marko; Olkkonen, Maria

Abstract

Previous studies suggest that to achieve color constancy, the human visual system makes use of multiple cues, including a priori assumptions about the illumination (“daylight priors”). Specular highlights have been proposed to aid constancy, but the evidence for their usefulness is mixed. Here, we used a novel cue-combination approach to test whether the presence of specular highlights or the validity of a daylight prior improves illumination chromaticity estimates, inferred from achromatic settings, to determine whether and under which conditions either cue contributes to color constancy. Observers made achromatic settings within three-dimensional rendered scenes containing matte or glossy shapes, illuminated by either daylight or nondaylight illuminations. We assessed both the variability of these settings and their accuracy, in terms of the standard color constancy index (CCI). When a spectrally uniform background was present, neither CCIs nor variability improved with specular highlights or daylight illuminants (Experiment 1). When a Mondrian background was introduced, CCIs decreased overall but were higher for scenes containing glossy, as opposed to matte, shapes (Experiments 2 and 3). There was no overall reduction in variability of settings and no benefit for scenes illuminated by daylights. Taken together, these results suggest that the human visual system indeed uses specular highlights to improve color constancy but only when other cues, such as from the local surround, are weakened.

Citation

Wedge-Roberts, R., Aston, S., Beierholm, U., Kentridge, R., Hurlbert, A., Nardini, M., & Olkkonen, M. (2020). Specular highlights improve colour constancy when other cues are weakened. Journal of Vision, 20(12), 1-22. https://doi.org/10.1167/jov.20.12.4

• Journal Article Type: Article
• Acceptance Date: Sep 7, 2020
• Online Publication Date: Nov 10, 2020
• Publication Date: 2020-11
• Deposit Date: Sep 10, 2020
• Publicly Available Date: Nov 20, 2020
• Journal: Journal of Vision
• Electronic ISSN: 1534-7362
• Publisher: Association for Research in Vision and Ophthalmology
• Peer Reviewed: Peer Reviewed
• Volume: 20
• Issue: 12
• Pages: 1-22
• DOI: https://doi.org/10.1167/jov.20.12.4
• Public URL: https://durham-repository.worktribe.com/output/1292580