APPARATUS AND METHOD FOR MEASURING SHARPNESS, APPARATUS AND METHOD FOR PROCESSING IMAGE, SHARPNESS MEASURING PROGRAM, IMAGE PROCESSING PROGRAM, AND STORAGE MEDIUM

摘要

PPROBLEM TO BE SOLVED: To provide an apparatus and method for processing an image that provides a digital image having preferable sharpness, and an apparatus and method for measuring sharpness that can obtain the optimum measurement value as sharpness strength used for the processing. PSOLUTION: A lightness luminance signal converting section 11 converts an inputted image signal into a lightness luminance signal indicating perceptually equivalent lightness or luminance, then a band processing section 12 applies differentiation processing to the lightness luminance signal to provide a differential image signal. A sharpness strength measuring section 14 calculates a histogram indicating a correspondence relation between a value of the differential image signal and the number of pixels, calculates a frequency value taking some percentage between the maximum in the histogram and 3-10 % of all number of pixels, and sets the value of the differential image signal corresponding to the frequency value as the sharpness strength. At this time, the sharpness strength may be corrected according to the attribute information acquired by an attribute information acquisition section 13. PCOPYRIGHT: (C)2006,JPO&NCIPI