1. A method of identifying the direction of characters in an image block, comprising: performing optical character recognition processing on the image block by assuming various directions as assumed character directions, respectively, to obtain sub image blocks, recognized characters corresponding to the sub image blocks and correctness measures thereof in each of the assumed character directions; determining a language group to which the characters in the image block belong; adjusting a correctness measure corresponding to a sub image block which corresponds to a recognized character not belonging to the determined language group in each of the assumed character directions; calculating an accumulative correctness measure in each of the assumed character directions based on the adjusted correctness measure; and identifying the direction of the characters in the image block according to the accumulative correctness measures.