Feature point based image watermarking with insertions, deletions, and substitution codes

In this paper we concentrate on robust image watermarking (i.e. capable of resisting common signal processing operations and intentional attacks to destroy the watermark) based on image features. Kutter et al.(7) motivated that well chosen image features survive admissible image distortions and hence can benefit the watermarking process. These image features are used as location references for the region in which the watermark is embedded. To realize the latter, we make use of previous work(16) where a ring-shaped region, centered around an image feature is determined for watermark embedding. We propose to choose a specific sequence of image features according to strict criteria so that the image features have large distance to other chosen image features so that the ring shaped embedding regions do not overlap. Nevertheless, such a setup remains prone to insertion, deletion and substitution errors. Therefore we applied a two-step coding scheme similar to the one employed by Coumou and Sharma(4) for speech watermarking. Our contribution here lies in extending Coumou and Sharma's one dimensional scheme to the two dimensional setup that is associated with our watermarking technique. The two-step coding scheme concatenates an outer Reed-Solomon error-correction code with an inner, blind, synchronization mechanism.