基于DWT最优多子图和SIFT几何校正的鲁棒水印算法

In order to improve the robustness of watermarking system, this paper proposed a DWT multi-subgraph based watermarking algorithm with PSO algorithm. The algorithm selected multiple subgraphs after DWT transform for DCT transform, then used PSO algorithm to find the optimal combination weights of multiple subgraphs. The algorithm embedded and extracted the watermark by using the spread transform QIM principle. To improve the performance of watermarking algorithm in resisting the geometric attacks, this paper proposed an anti-geometric attack method based on improved SIFT. It adopted a round based feature point description method to improve the SIFT algorithm. Before watermark extraction, it performed geometric correction processing by SIFT feature point matching. Experimental results show, based on the imperceptibility of watermark, the robustness of DWT multi-subgraph based watermarking algorithm with PSO algorithm is better than watermarking algorithm based on DWT single-subgraph. Watermarking system with improved SIFT algorithm can significantly improve the resistance to geometric attacks.