Attack characterization for effective watermarking

We present and analyze an approach to improve the performance of a broad class of watermarking schemes through attack characterization. Traditional robust watermarking methods use little information concerning the way in which the image is tampered to estimate the embedded watermark. In our novel scheme we propose adding two types of watermarks: reference and robust. The reference watermark is used to assess the way in which the marked image has been modified so that the robust watermark can be optimally extracted to maximize security. Analysis and simulation results are provided to demonstrate the significant performance improvement when the proposed approach is employed in an existing watermarking scheme.