Dissertation > Industrial Technology > Automation technology,computer technology > Computing technology,computer technology > General issues > Security and confidentiality > Encryption and decryption

The Research of Dual-Color Image Watermarking and MPEG4 Video Watermarking Algorithm

Author ZhangXiuLang
Tutor JiangZeTao
School Nanchang University of Aeronautics and
Course Applied Computer Technology
Keywords discrete cosine translation(DCT) digital watermarking human visual system(HVS) error-correcting bits robustness
CLC TP309.7
Type Master's thesis
Year 2008
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Digital Watermarking has become an effective method of copyright protection for digital products in the last ten years. As the complement of encryption, it has solved the problem of traditional cryptography that encrypted contents are not secure when have been decrypted. Therefore it has been studied and used widely as an effective method of knowledge copyright protection and preventing from sham for digital multimedia. However, there are still plenty of theoretical and practical difficulties to be solved in a new field of digital watermarking. The key point of applicable digital watermarking technique is to find out an algorithm which is low complexity, good security, invisibility and robustness. Some original algorithms in digital image and video watermarking field are proposed in this paper.Referring to a large number of domestic and foreign literature of digital image and video watermarking, a dual color images watermarking method based on error-correcting bits in discrete cosine translation domain and a blind MPEG4 video watermarking algorithm based on spread spectrum technology in discrete cosine translation domain are proposed after summing up those algorithm which have been proposed in previous authors’papers and they are implemented successfully in windows operating system, analyzing mainly their invisibility and robustness according to the experimental results. The color watermarking image is compressed in viewpoint of JPEG algorithm based on DCT in the dual color images watermarking method. Each component of the color watermarking image in the YCbCr color space is blocked 8×8 and done discrete cosine transform, and then extracting the former 15 DCT coefficients of each block after ordering of ZigZag, the other DCT coefficients assignment 0.The embedded color watermarking image is formed after ordering of inverse ZigZag and then IDCT. Extracting the former 15 DCT coefficients of each block from Row to Column in each component and then they are translated into symbols binary which they are Spread Spectrum to form a sequence, which is extended not overlap each other through 8 cycle to form another sequence. This sequence is XOR-ed with a pseudo random sequence with the same length as it. The host color image after DCT, the low-frequency is main energy of it and the high-frequency is the marginal information of it. The watermark information embedded in the low-frequency of DCT will affect the invisibility and it embedded in the high-frequency of DCT will affect the robustness. The watermark sequence is embedded in the middle-frequency and low-frequency of DCT in texture block of the host image combining human visual system. In the blind MPEG4 video watermarking algorithm based on spread spectrum technology in discrete cosine translation domain, a binary image transformed with Arnold scrambling is extended with not overlapping each other through 8 cycles to form another sequence, which is XOR-ed with a pseudo random sequence with the same length as it. The video frames are obtained from XVID codec and they are inverted to YCbCr color space, the video files are compressed by MPEG4. The Y components are DCT and then ordered by ZigZag, altering those DCT coefficients according to the watermark sequence and then the MPEG4 video embedded the watermark is obtained from the XVID codec. Extract the watermarking under their scope of the remainder which these DCT Coefficients of the MPEG4 video embedded the watermark divided the embedded strength and needn’t have the original MPEG4 video.The two digital watermarking algorithms proposed in this paper are programmed in the C++ Builder 6.0, the whole process of watermark embedded and the whole process of watermark extracted are demonstrated. Experimental results demonstrate that the watermarking is good invisibility and robustness.

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