An image processing apparatus includes an edge detecting portion for detecting an edge area of an input image signal and a lightness and chroma detecting portion for detecting a low lightness and low chroma area of the input image signal. An image processing such as edge emphasizing is performed for the edge area of black letters or lines decided by the detection signals of the edge detecting portion and the chroma detecting portion. The image processing apparatus further includes an edge enlarging portion 6 for enlarging the edge area detected by the edge detecting portion 4 and circuits 12 and 19 for converting color image data C, M and Y and black image data K so that C, M and Y color densities in the enlarged edge area is decreased and a black densities is increased. Thus, supporting a high definition, color drift in the edge portions of the black letters or lines of the color image becomes inconspicuous, so that the reproducing quality is improved.