Watermark location via back-lighting modelling and verso registration

Abstract

We consider the location of paper watermarks in documents that present problems such as variable paper thickness, stain and other damage. Earlier work has shown success in exploiting a computational model of backlit image acquisition --- here we enhance this approach by incorporating knowledge of surface verso features. Robustly removing recto features using established techniques, we present a registration approach that permits similarly robust removal of verso, leaving only features attributable to watermark, folds, chain lines and inconsistencies of paper manufacture. Experimental results illustrate the success of the approach.