An image processing apparatus includes a binarization section, a determination section and an area setting section. The binarization section binarizes a given image. The determination section determines whether or not a pixel to be determined is effective in accordance with the number of pixels of one value of a binary value in each of determination areas. Each of the determination areas are placed so as not to contain the pixel to be determined in the binarized image and so as not to overlap in a predetermined direction of the pixel to be determined. The area setting section sets an area including the pixel determined effective in the determination section.