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Proceedings Paper

Non-Linear Models Of Early Chromatic Processing
Author(s): Ron Gershon; Allan D. Jepson
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Paper Abstract

In this paper, we discuss two non-linear models of early chromatic processing as motivated by biological systems. Two aspects of the models are examined -- their spatio-chromatic characteristics as evident from linear analysis, and the way the operators built in these models respond to different stimuli. We show that both nonlinear models for cone responses can be subject to linear analysis under low contrast conditions. Analysis of simple opponent (Type I) operators show that these operators are inseparable in space and color. They exhibit color opponent behavior in low spatial frequencies, and monochromatic behavior for high spatial frequencies. Double-opponent operators behave as chromatic change detectors, which signal changes in the sign of the two chromatic components that comprise the input. As such, when using either model, they do not respond to multiplicative changes in intensity. The change of weights assigned to the center and the surround affects the null point by moving it to a different wavelength, both for the Type I and double-opponent operators. Because of the separability of the double-opponent operator, this feature can be used to tune the operator to detect inputs in a narrow band of wavelengths. The responses obtained from the two nonlinear models are in reasonable agreement with the responses in human color vision. This suggests that the models capture the appropriate qualitative behavior.

Paper Details

Date Published: 13 October 1987
PDF: 8 pages
Proc. SPIE 0845, Visual Communications and Image Processing II, (13 October 1987); doi: 10.1117/12.976496
Show Author Affiliations
Ron Gershon, Expert Systems Center, Allied Signal (Canada)
Allan D. Jepson, University of Toronto (Canada)

Published in SPIE Proceedings Vol. 0845:
Visual Communications and Image Processing II
T. Russell Hsing, Editor(s)

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