1,721,027 research outputs found
Corresponding color datasets and a Color Vision Model based on the OSA-UCS system
No full textThe most important part of any Color Appearance Model is the Chromatic Adaptations Transform (CAT), whose empirical ground is constituted by sets of corresponding colors, i.e. color pairs with equal appearance specification and belonging to different visual situations (different illuminants and/or different illumination levels). Today the CATs are reconsidered, since Brill and Mahy have shown their mathematical inconsistency. In 2004-2005 the author proposed an Adaptation Transform based on the Uniform Color Scale system of the Optical Society of America (OSA-UCS), where the visual adaptation transforms the cone activation stimuli into adapted stimuli. Today, only the OSAUCS system allows the definition of adapted stimuli. Two applications of this CAT are already published by requiring color constancy and using the definition of adapted stimuli given by OSA-UCS system. The present work considers all the available corresponding color datasets used for defining the usual CATs and 1) produces color-conversion matrices between all the visual situations considered for these corresponding color measurements; 2) shows the ambiguity existing in the definition of adapted stimuli, if not empirically defined; 3) proposes the measurements of adapted stimuli referred to the OSA-UCS system
Hypotheses for Chromatic Opponency Functions and their Performance on Classical Phychophysical Data
No full textGeneral hypothesis for the definition of chromatic-opponency functions are given in a black-box approach to the problem. It is supposed that the color signals in the visual color processing can be factorized into the product of the lightness times a pair of chromatic opponency functions and the whole chromatic processing consists of three independent processes: a linear transformation, a logarithmic compression, and a chromatic opponency actuation. The main chromatic opponency functions, obtainable by very general hypothesis on the symmetry and on the homogeneity degree, are supposed equal to the logarithms of tristimulus value ratios in a proper reference frame of the tristimulus space. The perceptual chromatic functions, individually with uniform scales, are a linear mixing of the main chromatic opponency functions. The Bezold–Brücke hue shift is not considered. A performance of these hypothesis is successfully realized on the OSA-UCS system, for extra macula vision, and on the chromatic discrimination ellipses, for macular vision. Unique hues are derived from the main chromatic opponency functions of spectral lights. © 2004 Wiley Periodicals, Inc. Col Res Appl, 30, 31–41, 2005; Published online in Wiley InterScience (www.interscience.wiley.com)
A deconvolution technique for colour-matching functions obtained by metameric matching of non monochromatic spectral lights
No full textPSYCHOMETRIC COLOR-VISION MODEL BASED ON THE OSA-UCS SYSTEM AND ELECTRONIC IMAGE COLOR CONVERSION
No full textISBN 978-961-6045-80-
Uniform-Scale Chromaticity Diagram with Angular Coordinates in Zero-Curvature Space
No full textJOURNAL OF THE OPTICAL SOCIETY OF AMERICA
Elecronic Image Color Conversion between Different Illuminants by Perfect Color-Constancy Actuation in a Color-Vision Model Based on the OSA-UCS System
No full textISBN: 978-0-89208-291-
Comparison between Color-Space Scales, Uniform Color-Scales Atlases and Color- Difference Formulae
No full textSpectral-reflectance-factor deconvolution and colorimetric calculations by local-power expansion
No full textC. Oleari, Color Opponency and Scale Uniformity in the OSA-UCS System: the Geometrical Structure
No full textA concise History of the Chromaticity Diagram, from Newton to the CIE Observer
No full textISBN 978-82-91313-46-
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