Visual sensitivity to color-varying stimuli

ABSTRACT We present the results of a study of the sensitivity of the human visual system (HVS) to spatially varying color stimuli. Sinusoidal grating patterns of different spatial frequencies were presented to six observers and the contrast required to just distinguish the pattern from the surrounding uniform field was determined. Tables and curves of contrast (measured in ELab) as a function of frequency were generated at different values of; the orientation ( horizontal, vertical and diagonal) of the pattern, the average luminance, the z and y c xi oknaticity co-ordinates, andthe direction of the variation of the stimulus in color space (luminance, red-green, and Llue-yllow). The results showthat the HVS is more sensitive to sinusoidal gratings oriented horizontally and vertically regardless of the type ofvariation. Furthermore, the HVS is more sensitive to luminance variations than it is to chromatic variations. Tablesand curves of the data are presented. 1. INTRODUCTION Over the past two or three decades, efforts have concentrated on relating the subjective measures of image qualityto more quantitative terms. Linear system analysis techniques have been successfully applied to problems involving