1. A computer readable storage medium having stored therein an output program causing a computer serving as an information processing apparatus to execute a process comprising: determining first pixels and second pixels, out of pixels that form a binary image, the first pixels forming an area equal to or greater than a predetermined size and having pixel values not different from pixel values of neighboring pixels, the second pixels forming an area not equal to or greater than the predetermined size; reducing the pixel values of the first pixels and the second pixels; and outputting the binary image with the reduced pixel values.