Coding and Synchronization: A Boost and a Bottleneck for the Development of Image Watermarking

This paper presents a theoretical analysis of the performance of a family of watermarking schemes formulated in the spatial domain. A general model for watermarking based on perceptual masking that boils down to an equivalent Gaussian channel is presented and characterized. Starting from the Gaussian equivalent, introduction of coding as a means of improving the performance of the watermarking system is fully justified and illustrative examples are presented. Some important classes of attacks can be readily analyzed with our results, both for the coded and uncoded cases. Finally, the synchronization problem is discussed through some examples, with disappointing results that lead to a final discussion.