SHARPNESS METRIC FOR ASYMMETRICALLY ENHANCED IMAGE AND VIDEO

摘要

A sharpness metric represents a control variable of manual (47) or automated (41) sharpness control systems for image and video acquisition, storage and reproduction systems. In manual systems usually one controllable parameter is adjusted seeking to maximize sharpness, within pre-established limits to avoid image distortion. A method for measuring sharpness (10) in an image or picture that may have been enhanced asymmetrically uses statistics from a Discrete Cosine Transformation on predetermined blocks of the image and compensates for asymmetry using information on a number of edge pixels (14) and an energy content of one or more vertical edges and one or more horizontal edges in each block (15). One embodiment for so doing determines a kurtosis­based sharpness metric of the image (12) and then compensates the kurtosis-based sharpness metric to account for differences in sharpness enhancement in a horizontal direction and a vertical direction (13).