Analysis of optically variable devices using a photometric light-field approach

Daniel Soukup; Svorad Štolc; Reinhold Huber-Mörk

doi:10.1117/12.2080108

4 March 2015 Analysis of optically variable devices using a photometric light-field approach

Daniel Soukup, Svorad Štolc, Reinhold Huber-Mörk

Proceedings Volume 9409, Media Watermarking, Security, and Forensics 2015; 94090R (2015) https://doi.org/10.1117/12.2080108
Event: SPIE/IS&T Electronic Imaging, 2015, San Francisco, California, United States

Abstract

Diffractive Optically Variable Image Devices (DOVIDs), sometimes loosely referred to as holograms, are popular security features for protecting banknotes, ID cards, or other security documents. Inspection, authentication, as well as forensic analysis of these security features are still demanding tasks requiring special hardware tools and expert knowledge. Existing equipment for such analyses is based either on a microscopic analysis of the grating structure or a point-wise projection and recording of the diffraction patterns. We investigated approaches for an examination of DOVID security features based on sampling the Bidirectional Reflectance Distribution Function (BRDF) of DOVIDs using photometric stereo- and light-field-based methods. Our approach is demonstrated on the practical task of automated discrimination between genuine and counterfeited DOVIDs on banknotes. For this purpose, we propose a tailored feature descriptor which is robust against several expected sources of inaccuracy but still specific enough for the given task. The suggested approach is analyzed from both theoretical as well as practical viewpoints and w.r.t. analysis based on photometric stereo and light fields. We show that especially the photometric method provides a reliable and robust tool for revealing DOVID behavior and authenticity.

Citation Download Citation

Daniel Soukup, Svorad Štolc, and Reinhold Huber-Mörk "Analysis of optically variable devices using a photometric light-field approach", Proc. SPIE 9409, Media Watermarking, Security, and Forensics 2015, 94090R (4 March 2015); https://doi.org/10.1117/12.2080108

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