Forensic Identification of Printed Documents

This chapter concentrates on those techniques that aim to extract a unique and reproducible forensic signature from a printed document or the substrate on which the document is printed. These techniques provide high levels of statistical robustness sufficient to uniquely identify printed documents. Such techniques are split into two categories: those that require the addition of special materials and processes to provide a random forensic signature that is very hard to copy, and those that make use of the natural randomness of the print process and the underlying substrate to generate the forensic signature. The chapter mostly concentrates on the latter technique. It discuses some general hardware (HW) requirements, and presents methods that use forensic printed marks, character glyphs and halftone images as the basis for forensic signature recovery. The chapter also illustrates the potential use of forensic authentication in the context of currency protection.