Paper fingerprinting using alpha-masked image matching

In this study, the authors examine the process of authenticating paper media using the unique fibre structure of a piece of paper (the so-called `paper fingerprint`) In particular, the authors look at methods to authenticate a paper fingerprint when text has been printed over the authentication zone. The authors show how alpha-masked correlation can be applied to this problem and develop a modification to this technique that is more closely matched to the requirements of this problem and produces an improvement in performance. They also investigate two methods of pixel inpainting to remove printed text or marks from the authentication zone and allow ordinary correlation to be performed. The authors show that these methods can perform as well as alpha-masked correlation. They derive confidence estimates for one of the matching processes. Finally, the authors investigate some methods for improving the robustness to forgery and rotation of the matching process.