Detection optimization for the DCT-domain image watermarking system

This paper proposes a detection optimization for the DCT-domain image watermarking system developed by Barni et al. The visual masking introduced in this scheme causes performance deterioration in the watermark detection. We therefore modify the searched watermark, by using linear algebra methods, taking into account the influence of the visual masking on the watermark detection. The optimized detection outperforms the standard one for both non-attacked images and images subjected to a number of standard attacks. In addition, it allows detection of very weak watermarks. The optimization process requires a few percents of the original DCT coefficients.