Informed watermark embedding in the fractional fourier domain

We propose an informed watermark embedding method in fractional Fourier domain. Detectability and imperceptibility of the watermark sequence constraints as well as real-valuedness in spatial domain are imposed on the resulting image using a set theoretic framework. Insertion of multiple bits without using a block based scheme is also a novel approach and provides improvement against synchronization attacks. The watermarked image is determined using the method of projections onto convex sets (POCS) to simultaneously satisfy the multiple constraints. A performance comparison between blind and informed embedding is illustrated and experimental results are presented to show the effectiveness of the informed method.