1. A sharpness enhancement processing apparatus for processing image data S set and output in a predetermined pixel density for enhancement of sharpness, using image data surrounding said image data S, comprising: range setting means for setting an area of said surrounding image data based on said predetermined pixel density; smoothed image data generating means for processing said image data S for smoothness using only said surrounding image data that falls within the area set by said range setting means, to thereby produce smoothed image data U; and image data generating means for generating sharpness-enhanced image data S* defined as S*=S+K.multidot.(S-U), using said image data S, said smoothed image data U and a predetermined sharpness enhancement coefficient K.