Sharpness, sharpness related attributes, and their physical correlates

In this paper we present a metric that predicts differences in perceptual sharpness from physical parameters extracted from CCD camera recordings of sine-grating and step-profile test images. Sharpness differences were induced by using five different high-end television sets to display natural colour images as well as by using blurred versions of these images. The metric is a two-step model that uses the perceptual strengths of three sharpnessrelated attributes on a intermediate level between the physical parameters and perceptual sharpness. The data obtained from category scaling experiments indicate that perceptual strength of sharpness is a linear combination of the perceptual strengths of the attributes detail rendering and contour rendering. It was found that differences in detail rendering correlate with differences in modulation depth of the sine gratings and that differences in contour rendering can be explained from the slope and overshoot parameters of the step-profiles.