Static Image-based Digital Watermarking Technology

Digital watermarking provides a novel way for the protection of intellectual property rights, and becomes a hot spot in the research of multimedia data security in recent years. The technique of DCT-Based digital watermarking for copyright protection of static image is studied in this paper.By studying JPEG compression and HVS theory, watermarking information is embedded in the DCT intermediate frequency coefficient part of the image. In order to enhance security level in the data transfers, matrix scrambling algorithm is used. After deeply analyzing the technical characteristics and requirements of image watermarking, two present algorithms are improved to enhance their imperceptibility and robustness, and two DCT-based image watermarking algorithms which can be applied to copyright protection are put forward in this paper. The first method is an improved DCT-based private watermarking algorithm. The embedment intensity of watermarking is enhanced by the quantization of the originality carrier image. The second method is a DCT-based blind watermarking algorithm. After analyzing the algorithm of intermediate frequency coefficient quantization processing blind watermarking, the robustness of watermarking is enhanced by correcting the watermarking image.Finally, a lot of experiments are performed to test the imperceptibility and robustness of the private watermarking algorithm and blind watermarking algorithm and the two improved algorithms. The experimental results indicate that the improved algorithms are more imperceptible and robust than the original algorithms.