Research Of Robust Watermarking In DCT Domain Based On Bézier Curve Of The First Degree

With the rapid development of computing and network technology, multimedia data is used more widely. At the same time, the multimedia security becomes an important and challenging research topic. Digital watermarking technique is an effective method for digital content protection such as copyright protection and becomes an important research area in the field of information hiding. Thus the research on digital watermarking is of great importance. This paper focuses on the approaches to improve the embedding and extraction of the robust watermarking based on the characteristics of digital images, under the condition that those approaches satisfy the security requirements.The thesis focuses on the digital image watermarking. Firstly, the background and the states of digital watermarking are introduced, and the basic concept and character, generic model, typical algorithms, attack analysis and evaluation of performance of digital watermarking techniques are discussed .Then a deep study and discussion on the structure of watermarking system are presented.Enlightened by the image fusion and the existence of research watermarking algorithms, we select Bézier curve of the first degree as the theoretical base for fusion of the embedded watermarking, we propose a new robust watermarking algorithm based on linear fusion and the discrete cosine transform theory. The thesis mainly carries on the following four aspects:①Do research on linear fusion and the discrete cosine transform theory, proposing an image fusion algorithm based on Bézier curve of the first degree, and then calculating the error value when the algorithm is used for image hiding. In order to avoid this error value, we divide watermarking information and realize the improvement of the algorithm.②Scramble the watermarking information and divide it, and then recombine each pixel, we have improved the extraction accuracy of the watermarking.③By using Hash function to select the watermarking embedding points of the blocked DCT coefficients, we improve the security of the algorithm; By embedding watermarking with Bézier curve of the first degree, we improve the invisibility and robustness of the watermarking.④Do simulational experiments, the experimental results are obtained without any attacks, under JPEG lossy compression and other attacks. Experimental results prove that the proposed algorithm has the watermark's imperceptibility and robustness of resisting attacks such as JPEG compression, cutting, noise etc.Finally, we review the entire work, and make the expectation of the direction for the future research.