An image processing apparatus of the present disclosure includes: a step detecting unit which detects a first step pixel and a second step pixel in the binary image and step directions of the first step pixel and the second step pixel; and an enlargement processing unit which inverts pixel values of pixels from the first pixel value to the second pixel value in a pixel area corresponding to the first step pixel in the enlarged image, and inverts pixel values of pixels from the second pixel value to the first pixel value in a pixel area corresponding to the second step pixel. The pixels of which pixel values are inverted are located at positions corresponding to its step direction. The number of the pixels of which pixel values are inverted corresponds to its step length in the binary image.