1. An image processing apparatus comprising: a composite image generator that generates a composite image by superimposing, on a document image of a document represented by document data, two-dimensional code images individually corresponding to a plurality of document elements included in the document; and a print controller that causes a printer to print the composite image, wherein the composite image generator determines positions of the two-dimensional code images corresponding to the document elements so that the positions do not overlap images of the document elements.