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Robust watermarking based on spread transform

Invisibility and robustness are two important performance indicators of watermarking algorithm. To improve the performance of watermarking algorithms, the visual model is introduced, and the most classic is the Watson model. However, the original Watson model is defective in resisting amplitude scaling. In this paper, we will propose a new improvement of the Watson model to overcome its shortcomings on amplitude scaling and not to change the contrast values of original model as much as possible. Then feature points matching based on scale-invariant feature transform (SIFT) algorithm is introduced to improve the performance of watermarking algorithm on resisting geometric attacks. While the traditional SIFT algorithm has high computational complexity, we will propose an improved SIFT algorithm different from used to reduce the computational time and still keep high correction accuracy. The combination of the improved SIFT algorithm and the watermarking algorithm can greatly improve watermark's robustness against geometric attacks. The experimental results show that the proposed algorithms not only keep better invisibility, but also optimize the robustness of resisting various attacks.