Research Of Digital Watermarking Algorithm Based On Contourlet

With the rapid development of the digital multimedia technology, it is being easier to reproduce, store and distribute the multimedia information. So how to protect the legitimate interests of copyright owners is becoming an urgent issue. The technique of digital watermark has been the main method of multimedia copyright protection. It is to embed the copyright information into digital original signal according to some particular algorithm. Thus, it can realize the copyright protection and authentication. And it has been the focus in the field of multimedia signal processing as an important branch of the information security technology. In the thesis, the contourlet transform has been studied and two specific watermarking schemes have been proposed. The main contributions of the thesis are as follows:First of all, the principles, characteristics and classification of the digital watermarking technology are summarized and explained, then the current performance of the watermarking algorithm evaluation criteria are introduced, all of which lay a foundation for the specific algorithm in next step.Secondly, the thesis proposes a image watermarking algorithm based on multiscale geometric analysis of contourlet transform. The binary image is chosen as the watermark. The watermark is embedded according to comparing the relationship of center and adjacent contourlet transform's coefficients of original image. Experimental results show that the algorithm has good transparency and strong resistance to attack, such as common compression, shear and noise. The watermark can be extracted from the watermarked image without the original image.At last, because there are similarities between video and image watermarking technology in application mode and design scheme. With the idea above, a video watermarking algorithm based on contourlet transform is proposed. The experimental result shows that the algorithm has good fidelity and robustness to the different attack, but how to improve resistance to MPEG is to be further study.As a new technology, there are still many problems that need to solve and does not touch on some topic in the development of digital watermarking. Finally, the thesis summarizes the digital watermarking technology and look forward to the development of this field.