Relationship between color discrimination threshold and suprathreshold color-difference perception

Haisong Xu, Hirohisa Yaguchi, Satoshi Shioiri

Research output: Contribution to journalConference articlepeer-review


Based on the psychophysical method of constant stimuli, an experiment was carried out, using CRT-generated stimuli and in CIELAB color space, to test the visual color differences in relation to colorimetric scales. The CIE Gray and Blue color centers, the most basic color and, perceptually, the most different color, respectively, were chosen, and the maximum average size of test color difference was 12 CIELAB angle E units. The resultant visual data, processed via probit analysis, were used to analyze the relationship between color discrimination threshold and suprathreshold color-difference perception. The equal color-difference contours, corresponding to all the visual scales, 4.0, 8.0, and 12.0 CIELAB angle E units, were well fitted into ellipses while maintaining the orientation of the threshold one, but the shapes were not completely same, especially, at Blue center. The comparisons between visual color differences and their colorimetric counterparts, in CIELAB angle E units or threshold units, show linear relations at both color centers, but the slopes were, in general, not equal to 45° and differed for all directions. Thus the suprathreshold color differences can be derived by enlarging the thresholds linearly but not uniformly, i.e. with different ratios for individual directions.

Original languageEnglish
Pages (from-to)662-665
Number of pages4
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 2001 Dec 1
Externally publishedYes
Event9th Congress of the International Colour Association - Rochester, NY, United States
Duration: 2001 Jun 242001 Jun 29


  • CRT-display
  • Color discrimination threshold
  • Color-difference perception
  • Method of constant stimuli
  • Probit analysis
  • Suprathreshold color difference

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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