Visual Neuroscience



COLOR CONSTANCY

Visual sensitivity to color errors in images of natural scenes


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

Article author query
aldaba ma   [Google Scholar] 
linhares jmm   [Google Scholar] 
pinto pd   [Google Scholar] 
nascimento smc   [Google Scholar] 
amano k   [Google Scholar] 
foster dh   [Google Scholar] 
 

Abstract

Simple color-difference formulae and pictorial images have traditionally been used to estimate the visual impact of color errors introduced by image-reproduction processes. But the limited gamut of RGB cameras constrains such analyses, particularly of natural scenes. The purpose of this work was to estimate visual sensitivity to color errors introduced deliberately into pictures synthesized from hyperspectral images of natural scenes without gamut constraints and to compare discrimination thresholds expressed in CIELAB and S-CIELAB color spaces. From each original image, a set of approximate images with variable color errors were generated and displayed on a calibrated RGB color monitor. The threshold for perceptibility of the errors was determined in a paired-comparison experiment. In agreement with previous studies, it was found that discrimination between original and approximate images needed on average a CIELAB color difference [Delta]Eab* of about 2.2. Although a large variation of performance across the nine images tested was found when errors were expressed in CIELAB units, little variation was obtained when they were expressed in S-CIELAB units.

(Received March 8 2006)
(Accepted March 9 2006)


Key Words: Color science; Color differences; Color reproduction; Natural scenes; Complex images.

Correspondence:
c1 Address correspondence and reprint requests to: Sérgio M.C. Nascimento, Department of Physics, Minho University, Campus de Gualtar, 4710-057 Braga, Portugal, E-mail: smcn@fisica.uminho.pt