To cut out a character and the like which are relatively darker than a background and are written with a pen and so on at a high speed, to use the cutting-out of a character and the like as pre-processing for character recognition, and to emphasize an object so as to hardly damage determinability of a character, a figure and the like to binarize the same. Attention is paid to that a character written with a pen and so on is relatively darker than a background, and a relative density of the character to a periphery thereof is obtained to binarize the same, thus emphasizing an object such as a character.