Surface Color Perception in Three-dimensional Scenes: Estimating, Representing and Discounting the Illuminant

Wednesday, March 8, 2006 - 10:30am - 11:30am
EE/CS 3-180
Laurence Maloney (New York University)
Joint work with Katja Doerschner, Huseyin Boyaci.

Researchers studying surface color perception have typically used
stimuli that consist of a small number of matte patches (real or
simulated) embedded in a plane perpendicular to the line of sight
(a Mondrian, Land & McCann, 1971). Reliable estimation of surface
properties analogous to color is a difficult if not impossible
computational problem in such limited scenes (Maloney, 1999). In more
realistic, three-dimensional scenes the problem is not intractable, in
part because considerable information about the spatial and spectral
distribution of the illumination is usually available. We describe a
series of experiments that (1) explore how the human visual system
discounts the spatial and spectral distribution of the illumination
(SSDI) in judging matte surface color and (2) what cues the visual
system uses in estimating the SSDI of in a scene. We find that the
human visual system uses information from cast shadows and specular
reflections in estimating the SSDI and, when more than one cue type is
present, combines these cues effectively. The SSDI can be very complex
in scenes with many different light sources. We examine (3) the limits
of human visual representation of the SSDI, reporting an experiment
intended to tests these limits. Our results indicate that the human
visual representation of the SSD of the illumination in a scene is well-
matched to the task of perception of matte surface color perception.

Land, E. H. & McCann, J. J. (1971), Lightness and retinex theory.
Journal of the Optical Society of America, 61,1-11.
Maloney, L. T. (1999), Physics-based approaches to modeling surface
color perception. In Gegenfurtner, K. R., & Sharpe, L. T. [Eds]
(1999), Color Vision: From Genes to Perception. Cambridge, UK:
Cambridge University Press, pp. 387-422.