Based On Chaos And Dct Digital Watermarking Algorithm

Digital watermarking as a new technology to provide copyright protection and authentication of multimedia data has been developing rapidly since 1990's, it be-comes an internationally hot topic at present. Digital watermarking technology allows users to imperceptibly embed a specifically signal------the watermarking signal into the multimedia data such as image, text, video and audio by a certain algorithm in or-der to protect copyright of multimedia data.This dissertation does research on the image digital watermarking algorithm highlighted . The main contributions are summarized as follows:(1)The fundamental contents such as basic features, purpose, significance and the current development status, classification and the general frame of digital watermark-ing are introduced in this paper,and some classical algorithms are also sur-veyed.These contents provide theoretical basis for the digital watermark algorithm's proposal and realization.(2)Introduced several watermarking scrambling methods that are commonly used currently, and focuses on how to use Arnold Transform and Chaos Theory to realize the watermark scrambling, meanwhile we improved the original chaos scrambling algorithm, the experimental results show that it can enhance the sensitivity of the chaos sequence.(3) Two digital watermarking algorithms based on DCT domain were proposed in this paper.The first algorithm introduced an embedding process of a pseudo sequence. This algorithm embedded the watermark information into the DC coefficients which generate by discrete cosine transform on the original image. According to the energy of these DC coefficients, arranging how to embed the watermark information. And the location information can be regarded as a key when extracting the watermark infor-mation, the experiment results show that the algorithm gets a good compromise in the performance of invisible and robustness. The second algorithm is a dual watermark algorithm. In order to improve the robustness of the algorithm ,this algorithm used the improved error correction coding technology,dither modulation technology and bit flat-decomposition technology and so on.The testing value of PSNR and NC is great, it proves that the algorithm has a good performance of invisibility and robustness.