On Digital Watermarks
In this paper, we introduce the concept of key-dependent basis functions and discuss its applications to secure robust watermarking for copyright protection and to designing secure public black-box watermark detectors. The new schemes overcome a possible security weakness of global, non-adaptive schemes that apply watermark patterns spanned by a small number of publicly known basis functions. The watermark is embedded into the projections of an image onto the secret set of key-dependent functions (patterns). The robustness of the watermarking scheme with respect to filtering, lossy compression, and combinations of many other attacks is studied. Finally, we propose a candidate for a watermarking scheme that enables the construction of a secure public watermark detector.
Keywords: Robust image watermarking, attacks, orthogonal patterns, secure public watermark detector