A segmentation process section classifies signals of pixels in input image data into respective signals of a black text/low density area, a black text/high density area, a color text area, and an area other than a text area. A black generation and under color removal section performs an under color removal process with respect to the signal of the black text/low density area so that an amount of UCR is a middle value (C, M, Y) of signals indicative of color component density levels. Consequently, it is possible to prevent color fringing and a white spot at a time when chromatic aberration occurs in the input image data.