A Model of the Formation of a Self-Organized Cortical Representation of Color

Copyright 2005 Society of Photo-Optical Instrumentation Engineers. This paper was (will be) published in Human Vision and Electronic Imaging and is made available as an electronic reprint [preprint] with permission of SPIE. Single print or electronic copies for personal use only are allowed. Systematic or multiple reproduction, distribution to multiple locations through an electronic listserver or other electronic means, duplication of any material in this paper for a fee or for commericial purposes, or modification of the content of the pater are all prohibited. By choosing to view or print this document, you agree to all the provisions of the copyright law protecting it.

In this paper we address the problem of understanding the cortical processing of color information. Unravelling the cortical
representation of color is a difficult task, as the neural pathways for color processing have not been fully mapped, and there are few computational modelling efforts devoted to color. Hence, we rst present a conjecture for an ideal target color map based on principles of color opponency, and constraints such as retinotopy and the two dimensional nature of the map.

We develop a computational model for the cortical processing of color information that seeks to produce this target color map in a self-organized manner. The input model consists of a luminance channel and opponent color channels, comprising red-green and blue-yellow signals. We use an optional stage consisting of applying an antagonistic centersurround filter to these channels. The input is projected to a restricted portion of the cortical network in a topographic way.

The units in the cortical map receive the color opponent input, and compete amongst each other to represent the input. This competition is carried out through the determination of a local winner. By simulating a self-organizing map for color according to this scheme, we are largely able to achieve the desired target color map. According to recent neurophysiological ndings, there is evidence for the representation of color mixtures in the cortex, which is consistent with our model. Furthermore, an orderly traversal of stimulus hues in the CIE chromaticity map correspond to an orderly spatial traversal in the primate cortical area V2. Our experimental results are also consistent with this biological observation.

By: A. Ravishankar Rao; Guillermo Cecchi; Charles Peck; James Kozloski

Published in: SPIE Proceedings, volume 5666, (no ), pages 17-26 in 2005


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