A method of controlling an image processing apparatus, and an image processing apparatus to carry-out the method. The edge pixels of a black character may be evaluated to improve visibility of edge pixels and to enhance the blackening of the edge pixels when the evaluated edge pixels are determined to be the actual edge pixels of the original image and to correct the edge pixels to be suitable for original background pixel values and to brighten the edge pixels when the evaluated edge pixels are determined to be the actual background pixels of an original image. The black character may be enhanced so that the actual black character becomes blacker and that the background pixels become brighter to improve the visibility of the black character. The black character may be distinguished from a scanned image, the print thickness of the distinguished black character may be controlled, and the black character having controlled print thickness may be printed out using only a K color.