METHOD OF ENHANCING IMAGE SHARPNESS FOR IMAGE REPRODUCTION USING SHARP/UNSHARP SIGNAL PROCESSING

An original image is read with an image reader for each pixel, whereby color component signals (Yi, Mi, Ci, Ki) expressing the original image are obtained. A sharp signal generator extracts the gray component from the combination of the color component signals, to output the gray component as a sharp signal (S.sub.O). The difference between the sharp signal (S.sub.O) and an unsharp signal (U) is linearly combined with the color component signals, to thereby give sharpness-enhanced signals (ES.sub.Y, ES.sub.M, ES.sub.C, ES.sub.K).