Image Descriptors for Displays

Abstract

Abstract : This report summarizes our experimental and theoretical results on the perception of displayed information. This research is concerned with four issues: (1) the effect of color on pattern recognition. (2) the measurement of statistical estimates for luminance and chrominance information in pictorial scenes, (3) the relationship between perceived changes in image sharpness resulting from changes in display modulation transfer, and (4) the development of a unified display descriptor to model the perception of both luminance and chrominance information. In this report we present the results of a series of experiments that established the relationship between our sharpness descriptor, the visual capacity, and the subjective sharpness of displayed images. The just-noticeable difference (jnd) in image sharpness was measured as a function of display bandwidth. At high spatial frequencies these measurements were found to be in excellent agreement with the assertion that display sharpness is mediated by the perceived rms gradient content of an image: a quantity proportional to the square root of the visual capacity. The addition of chrominance information to a black-and-white image was not found to appreciably affect the perception of image sharpness. Finally, the measured results on the subjective sharpness for both pictorial images and single-transition luminance edges proved to be indistinguishable. We feel that this result supports the contention that edge transitions are important in determining image sharpness in pictorial scenes.