1. A device for binarizing an image, comprising: an input part for receiving an image; a block classification part for dividing the received image into blocks, and classifying the divided blocks into character blocks and background blocks; an edge enhancement part for enhancing edges of each character block classified by the block classification part, using relations between neighboring pixels in the character block classified by the block classification part, and generating a threshold for distinguishing character pixels and background pixels of the character block; and a binarization part for binarizing pixels of character blocks output from the edge enhancement part into a first brightness value for character pixels and a second brightness value for background pixels by comparing the pixels of the character blocks with the threshold, and binarizing pixels of background blocks output from the block classification part into the second brightness value.