1. An image processing apparatus, comprising: a first memory that stores a first document file; a second memory that stores a second document file obtained by revising the first document file; an extraction unit that extracts 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 an extracted area specifying file generation unit that generates a file specifying the revision area extracted by the extraction unit, wherein an appearance of the revision area is changed on the generated file.
6. The image processing apparatus according to claim 1 , wherein: the second document file is obtained by scanning a paper document.