Commercial anticounterfeit products using machine vision
Patrick J. Smith, Phelim O'Doherty, Carlos Luna, Sean T. McCarthy · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2004
We present recent commercial anti-counterfeit projects that use machine-vision principles, to either verify genuine documents or trace the origin of counterfeits. In the first case we show how the characteristic nature of a reflection hologram, as used on a credit card, can be used to verify it quickly and economically. Many counterfeit holograms can be discriminated from a genuine example by a two-step test: first, that the visible object displayed by the hologram has the correct form when viewed at a given angle, and second, that the object changes in the correct way as the viewing angle is varied. Both of these can be implemented using a machine-vision system as we describe. Another application of machine-vision techniques in an anti-counterfeit context is their use in forensic investigation. We demonstrate how the origin of compact disks can be traced using marks in the outer surface, by imaging a magnified portion of the CD surface under darkfield illumination to maximise outer surface features while suppressing reflections from the internal data surface. We show that CDs from the same pressing machine exhibit matching defect patterns under darkfield illumination. This technique can be used to trace the origin of a sample counterfeit CD.