1. An image processing apparatus, comprising: an image reading section configured to read a document and to generate an image data, and a processing unit configured to perform image processing to the image data, wherein the processing unit includes: an area determination unit configured to determine, upon acquiring a first image data for a first document and a second image data for a second document, whether a text area or an image area of the second image data matches an initial text area or an initial image area that has initially appeared in the first image data; an area processing unit configured to execute, when the text area or image area of the second image data matches the initial text area or initial image area as a result of the determination, processing of reducing the image data of the matching text area or image area about the second image data; and an area adjustment unit configured to generate one new image data corresponding to the second document by using the data-reduced area resulting from the processing, and using a mismatched text area or image area.