Verifying Document Integrity

This chapter explains the main image analysis approaches used to verify document integrity in the context of printable and scanable documents. Printing and scanning documents introduces degradations, which pose a major challenge for integrity verification methods. In cases of forgery, a document image may be modified in different ways using image or text editing software. Imitation fraud is the reproduction of the intrinsic properties of the document, including font characteristics such as type, size and color. Scanned documents are visually similar to originals, but are deformed by the print and scan process. Active approaches aim to protect a document by introducing security elements in the form of extrinsic fingerprints that are used for future verification. There are two main types of approach: watermarking and digital signatures. Printer identification can be carried out at different levels: in terms of printer type brand, or model.