A DCT-based Digital Watermarking Algorithm for Images

A blind watermarking algorithm based on DCT is suggested in this paper. Achieving blind extracting of watermarking algorithm would generally reduce the robustness and invisibility. The key of this algorithm is to minimize such losses as much as possible to meet the requirement of applications. This paper has taken the following measures to improve the performance of the algorithm:use of chaotic sequences to scramble watermark. Taking advantage of the relationship among the DCT coefficients and making many experiments to find the most appropriate DCT coefficients,this algorithm realized a good trade-off between the robustness and invisibility. The experiments showed that the performance of the algorithm can meet the design requirements.