Paper Fingerprinting Using alpha-Masked Image Matching

In this paper, we examine the problem of authenticating paper media using the unique fiber structure of each piece of paper (the so-called "paper fingerprint"). In particular, we look at methods to authenticate paper media when text has been printed over the authentication zone. We show how alpha-masked correlation [Fitch05] can be applied to this problem and develop a modification to alpha-masked correlation that is more closely matched to the requirements of this problem and produces an improvement in performance. We also investigate two methods of pixel inpainting to remove printed text or marks from the authentication zone and allow ordinary correlation to be performed. We show that these methods can perform as well as alpha-masked correlation. Finally two methods of improving the robustness to forgery are investigated.