An image processing apparatus includes an edge detecting unit which identifies an area of given image data as a gradation sequence area and a character/line art area and which outputs edge information of the character/line art, a level converting unit which generates a strength modulation signal so as to emphasize an edge of the character/line art area, a laser driver which outputs a laser drive signal in order to form a picture dot larger than a standard size in response to the strength modulation signal. Further, according to the present invention, it is possible to print an image with emphasizing an edge portion of a character/line art by a laser printer.