High Resolution Imaging for Forensics and Security

Abstract

Printing provides innate forensic capabilities useful for product security as a consequence of the microscopic stochastic nature of the printing process itself and ink/substrate interaction during printing. This is especially true for substrates with a high degree of surface roughness/porosity, such as office paper, recycled paper, cardstock and packaging. Further imperfections are incurred during high speed printing, which taxes the limitations of the printing processes. These imperfections, consistent with reduced print quality, can be used serendipitously to provide a unique identifier for any printed symbol. This paper describes the hardware design for an imaging device that can analyze, with 7600 lines/inch resolving capability over a relatively large field of view of 6.6 x 4.9mm, any printed mark—from character to glyph to outline of an image—with high mark specificity. Combined with image analysis software written to describe the interface, or boundary, between ink-covered and ink-free substrate, this device, dubbed the Dr. CID (Dyson Relay CMOS Imaging Device [1]), can provide simultaneous image authentication and forensics.