1. An image processing apparatus comprising: a binarization section that binarizes a given image; a determination section that 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, wherein 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; and an area setting section that sets an area including the pixel determined effective in the determination section.