A neural model of chromatic induction in uniform and textured images and psychophysical detection of non-opponent chromatic qualia.

摘要

Color is a complex and rich perceptual phenomenon that relates physical properties of light to certain perceptual qualia associated with vision. Hering's opponent color theory, widely regarded as capturing the most fundamental aspects of color phenomenology, suggests that certain unique hues are mutually exclusive as components of a single color. According to his theory, a color cannot be reddish-green or bluish-yellow. This thesis describes research in which this claim is tested experimentally. Results obtained in psychophysical experiments with solid and textured images demonstrate perception of opponent mixtures (forbidden colors), thereby suggesting that the color opponent theory is inadequate as a perceptual model of color contrast.;In certain configurations spatio-chromatic interactions lead to a color induction---a shift in perception of color attributed to a surface, caused by spectral properties of surrounding areas. A neural model of chromatic induction presented in this thesis predicts the magnitude of this shift as a function of certain geometrical properties of an image and luminance contrasts between the adjacent areas. The model proposes a key neural circuit responsible for chromatic induction in solid and textured images. Computer simulations illustrate the model's compatibility with perceptual outcomes in color induction displays. This thesis analyzes the model's performance by varying geometrical and contrast properties of stimuli in a number of computer simulations. Simulation results compare favorably with previously published color induction data.;The neural model of chromatic induction also addresses the direction of chromaticity shift in color space associated with chromatic induction. The model proposes a layer responsible for spatio-chromatic interactions based on neural units with dual spatially and chromatically-opponent kernels. The output from this layer represents four independent color qualia: red, green, blue, and yellow. Computer simulations of the model's spatio-chromatic interactions demonstrate non-opponent relations of primary hues, in agreement with the results obtained in psychophysical experiments. The structure of hue space emerging from spatio-chromatic interactions is four-dimensional and non-opponent, therefore inconsistent with the hue space implied by Hering's opponent color theory.