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Comparison of color and luminance contrast: apples versus oranges?
Switkes, E; Crognale, M A.
  • Switkes E; Department of Chemistry, University of California, Santa Cruz 95064, USA. switkes@chemistry.ucsc.edu
Vision Res ; 39(10): 1823-31, 1999 May.
Article en En | MEDLINE | ID: mdl-10343874
Using a spatial, forced-choice, matching protocol, we have measured observers' ability to equate the contrasts of sinusoidal gratings which vary along differing directions in a 3-dimensional color space. In a given experiment, the observer obtained a perceptual match between the contrasts of two gratings whose chromaticities or luminances varied along differing chromatic directions which were selected from among five axes: an achromatic luminance axis (lum), an isoluminant axis where only S-cone activation varied (S-axis), an isoluminant axis where L- and M-cone activation varied in a complementary manner (LM-axis), an axis where only L-cone activation varied (L-axis), and an axis where only M-cone activation varied (M-axis). Even though these chromatic axes were chosen to activate independent mechanisms involved in the early stages of spatiochromatic visual processing, and despite the distinctly differing appearance of patterns from variations along differing directions, we find that observers can reliably make such pairwise contrast matches. Furthermore there is reasonable consistency of matching contrasts among observers and the pairwise contrast matches exhibit the properties of homogeneity and transitivity. This observed homogeneity and transitivity allows, for each color direction, the specification of a single scaling factor which relates perceptual contrast to physical contrast.
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Banco de datos: MEDLINE Asunto principal: Reconocimiento Visual de Modelos / Sensibilidad de Contraste / Percepción de Color Tipo de estudio: Prognostic_studies Límite: Humans / Male Idioma: En Año: 1999 Tipo del documento: Article
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Banco de datos: MEDLINE Asunto principal: Reconocimiento Visual de Modelos / Sensibilidad de Contraste / Percepción de Color Tipo de estudio: Prognostic_studies Límite: Humans / Male Idioma: En Año: 1999 Tipo del documento: Article