Results from psychophysics and single-unit recordings suggest that color vision comprises multiple stages of processing. Postreceptoral channels appear to consist of both a stage of broadly tuned opponent channels that compare cone signals and a subsequent stage, which includes cells tuned to many different directions in color space. The chromatic visual evoked potential (crVEP) has demonstrate...

We have examined how color appearance varies with spatial pattern. Subjects set color-matches between a uniform, 2 deg matching field and bars within squarewave patterns (1,2 and 4 c/deg) or the superposition of these squarewaves. The matches were set using squarewaves and squarewave mixtures with many different colors and contrasts. The color-matches satisfied the basic properties of a linear ...

This work concentrates on the problem of watermarking embedding and optimum detection in color images through the use of spread spectrum techniques, both in space (Direct Sequence Spread Spectrum or DSSS) and frequency (Frequency Hopping). It is applied to RGB and opponent color component representations. Perceptive information is considered in both color systems. Some tests are performed in or...

A symmetrical model of color vision, the decoding model as a new version of zone model, was introduced. The model adopts new continuous-valued logic and works in a way very similar to the way a 3-8 decoder in a numerical circuit works. By the decoding model, Young and Helmholtz's tri-pigment theory and Hering's opponent theory are unified more naturally; opponent process, color evolution, and c...

|Image halftoning converts a high-resolution image to a low-resolution image, e.g. a 24-bit color image to a three-bit color image, for printing and display. Vector error di usion captures correlation among color planes by using an error lter with matrix-valued coe cients. In optimizing vector error lters, Damera-Venkata and Evans transform the error image into an opponent color space where Euc...

This study addresses a fundamental question concerning the number of cortical, i.e., higher order mechanisms in color vision. The initial subcortical stages in color vision can be described by three cone mechanisms, S, M, L, and three pairs of second-stage mechanisms (achromatic L + M and -L - M, chromatic S - (L + M) and -S + (L + M), and chromatic L - M and M - L). The further mechanistic des...

Mechanisms of color vision in cortex have not been as well characterized as those in sub-cortical areas, particularly in humans. We used fMRI in conjunction with univariate and multivariate (pattern) analysis to test for the initial transformation of sub-cortical inputs by human visual cortex. Subjects viewed each of two patterns modulating in color between orange-cyan or lime-magenta. We teste...

This study investigated appropriate methodologies for displaying hyperspectral imagery based on knowledge of human color vision as applied to Hyperion and AVIRIS data. Principal Component Analysis (PCA) and Independent Component Analysis (ICA) were used to reduce the data dimensionality in order to make the data more amenable to visualization in three-dimensional color space. In addition, these...