Visual Neuroscience



SURFACE COLOR PERCEPTION

Color constancy in natural scenes with and without an explicit illuminant cue


KINJIRO  AMANO  a1 c1 , DAVID H.  FOSTER  a1 and SÉRGIO M.C.  NASCIMENTO  a2
a1 Sensing, Imaging, and Signal Processing Group, School of Electrical and Electronic Engineering, University of Manchester, Manchester, United Kingdom
a2 Department of Physics, Gualtar Campus, University of Minho, Braga, Portugal

Article author query
amano k   [Google Scholar] 
foster dh   [Google Scholar] 
nascimento smc   [Google Scholar] 
 

Abstract

Observers can generally make reliable judgments of surface color in natural scenes despite changes in an illuminant that is out of view. This ability has sometimes been attributed to observers' estimating the spectral properties of the illuminant in order to compensate for its effects. To test this hypothesis, two surface-color-matching experiments were performed with images of natural scenes obtained from high-resolution hyperspectral images. In the first experiment, the sky illuminating the scene was directly visible to the observer, and its color was manipulated. In the second experiment, a large gray sphere was introduced into the scene so that its illumination by the sun and sky was also directly visible to the observer, and the color of that illumination was manipulated. Although the degree of color constancy varied across this and other variations of the images, there was no reliable effect of illuminant color. Even when the sky was eliminated from view, color constancy did not worsen. Judging surface color in natural scenes seems to be independent of an explicit illuminant cue.

(Received March 8 2006)
(Accepted March 8 2006)


Key Words: Color constancy; Sky; Natural scenes; Illuminant estimate; Spatial cone-excitation ratios; Specular highlights.

Correspondence:
c1 Address correspondence and reprint requests to: Kinjiro Amano, Sensing, Imaging, and Signal Processing Group, School of Electrical and Electronic Engineering, University of Manchester, Manchester M60 1QD, UK. E-mail: k.amano@manchester.ac.uk