1. An image processing apparatus comprising: an edge pixel extractor for extracting edge pixels from an input image; a first histogram generator for generating a first histogram based on a luminance value of each of said edge pixels; a second histogram generator for generating a second histogram based on a minimum luminance value among the luminance values of pixels neighboring each of said edge pixels; a static threshold calculator for obtaining a static threshold based on said first histogram and said second histogram; and a binarization unit for binarizing said input image by using said static threshold.