Research And Implementation Of Dct-based Watermarking Algorithm

With the rapid development of the Internet and the wide range of applications of the computer, digital copyright protection issue has become one of the problems which urgently need to be resolved in the field of information security. Watermarking is one of the effective technical means which can protect the copyright of media, and authenticate the content of multimedia.Based on the detailed description of the basic principles, features and design process of the digital watermarking technology, this paper compares several typical watermarking algorithms and briefly introduces some common watermark attacks. Besides according to what has been learned, this paper summarizes the main problems in the digital watermarking technology and also gives us some countermeasures for each related attack. Having made a thorough research on robust digital watermarking technology based on Discrete Cosine Transform and combined with genetic algorithm, image scrambling technology and human visual characteristics respectively, we embed the watermark into the AC and DC components of carrier image. The main content of the paper are as follows:1. Proposed a new algorithm which embed the watermark into the DC component of the discrete cosine transform. The algorithm is based on the characteristics of human visual system, scrambled the watermark image by Arnold transform firstly, then embed it into the carrier image of the DC component, experiment shows that the hidden of the method is better and can withstand a certain amount of cutting and compression coding types of attacks, it is a robustness method.2. A robust image watermark algorithm based on Genetic Algorithm is proposed in this paper. Watermark embedding is modeled as a constrained optimization problem, By choosing proper fitness functions, make use the advantages of global search and parallelism of the Genetic Algorithm, select the appropriate fitness to determine the embedding location and strength, well solved the rounding error, achieved the optimal choice, in addition to improved the efficiency, the contradiction between robustness and fidelity is conciliated. 3. A robust watermarking algorithm which used double encryption method for the original image is proposed, which encrypted with the Logistic chaotic sequence, then proceeded with Hilbert position scrambling transformation, to make the watermark information safer. The randomness of chaotic sequence ensures robustness of the watermark, the Hilbert position scrambling transformation make the watermark more secure, effectively prevent the kinds of attacks. Experiments show that the method is simple, and more robustness.