10. An image processing method, comprising the steps of: storing a first document file; storing a second document file obtained by revising the first document file; extracting a revised area of the second document file based on the first document file corresponding to the second document file and the second document file; and generating a file specifying the revised area, wherein an appearance of the revision area is changed on the generated file, and wherein at least one of the steps is executed using a processor.
12. The image processing method according to claim 10 , wherein: the first document file and the second document file are obtained by scanning paper documents.