Research On Algorithm Of Digital Image Watermarking

The popularity of internet and the rapid development of digital technology are a two-face sword. On one hand , it brings great convinence on people's daily life, on the other hand, it aggravates the copyright violation. Digital watermarking, an important technology of information hiding, plays a more and more important roles in the copyright protection and content authentication. This thesis presents two algorithms in the copyright protection and content authentication, based on the introduction of the basic theory and framework of digital image watermarking technology. The main work of this thesis is as follows:1. the thesis proposes a watermarking algorithm for digital image based on SVD and DWT. To solve the contradiction between the robustness and transparency, the article uses the human visual system(HVS). The watermark can be embedded to the image adaptively based on the JND(just noticeable difference). It is no need the original image when extracting the watermark. The experiment is realized on the platform of matlab 2007R,and the experiment result shows that the algorithm is robust to the common signal processing technology and some malicious attacks.2. By taking full advantage of the masking characteristics of the HVS(Human Visual System), the thesis first presents a semi-fragile watermarking scheme which embeds the level-line, extracting from the image, in the DWT(Discrete Wavelet Transform) domain. It is no need the original image when extracting the watermarking. Moreover, when detecting and locating tampered areas, the original watermark is not necessary. The experiment results show that the algorithm has a good invisibility and high robustness against non-malicious attacks, and also can locate the tampered areas roughly.In the end of the thesis is the summary, state briefly what needs to reform.