1. A document processing apparatus comprising: a processor that functions as a character segmentation unit that segments a plurality of character images from a document image; a character image classifying unit that classifies the plurality of character images to categories corresponding to each of the plurality of character images; an average character image obtaining unit that obtains average character images for each of the categories of the plurality of character images classified by the character image classifying unit; a character recognizing unit that performs a character recognition to character images classified into the categories using the average character images of the categories; an output unit that outputs character discriminating information as a character recognition result obtained by the character recognizing unit; and a correcting unit that corrects the character discriminating information of a character image among the plurality of character images, wherein the correcting unit includes a dictionary including a plurality of morphemes, and performs a morphological analysis to extract a morpheme from the character discriminating information of the character, and the correcting unit, in a case where there is no morpheme in the dictionary corresponding to the extracted morpheme, generates a new category, classifies the character image to the new category in the character discriminating information of the character image.