Study On Application Of Digital Watermark Algorithms

The development background, basic principle and system model of digital watermark technique are introduced in this thesis, based on which ideal watermark algorithms are presented: spatial domain watermark algorithm based on information substitution, and the transform domain algorithm based on DCT domain and algorithm based on wavelet transform domain are presented. The watermark algorithm based on information substitution presented in this paper makes use of the character of human vision to image perception, human eyes cannot find the image change when part of the pixels of the original image are changed. The watermark is compressed and the watermark is embedded in part of the pixels of the original image, then the watermark-hiding algorithm based on information substitution can be realized. The watermark algorithm based on information substitution can be used to the information hiding of single or multi watermark images.For the watermark algorithm based on transform domain, the sensitivity to low frequency of human vision system is thought over, but many image process is for low frequency signal and little watermark in low frequency area cannot influence the image quality. To promote the robustness better, watermark algorithm based on DCT domain to embed in low frequency area and the watermark algorithm based on wavelet transform are studied. The watermark algorithm based on wavelet transform processes the transform between RGB color coordination and YUV color coordination firstly, and then serial wavelet transform is processed to complete watermark embedding. The experimental result shows the feasibility and efficiency of the algorithms. Lastly, the development of digital watermark system based on watermark algorithm presented above is discussed detailed, and main functions of the digital watermark system software and examples are introduced.