The Research And Implementation Of Digital Watermarking Algorithm Based On The Chaos Encryption And Wavelet Transformation

With the fast development of digital communication ,network and computer technology, multimedia application becomes popular. However, it also brings some problems, such as pirate, illegal copy etc. Copyright protection has become a key problem for multimedia. Digital watermarking, as one of the ways to resolve this problem, has been researched much and got notable achievements.We studied the still color image watermarking. And a meaningful watermarking algorithm based on chaos mapping and wavelet transform was proposed. The meaningful digital watermark is more readable, practical and intuitional compares with the traditional pseudo random sequences. But it has two difficulties to solve. One is that it must have some merits of pseudo random when watermark embedded, the other is that it has very high correctness when watermark detected. We solved these two problems in this dissertation.A binary image encryption Algorithm of chaos sequence based on Logistic mapping was proposed, The algorithm has some merits of strong security, easy realization and the encrypted watermark image has a good pseudo random feature.We applied blind detection technology, which means that original image is unnecessary when detecting watermark. Now many watermarking algorithms apply non-blind detection, which needs original image and limits applications on copyright protection.A robust watermark algorithm based on chaos encryption and wavelet transform is proposed. Making use of masking peculiarity of human visual system, the watermark image is adaptive embedded into the blocked lowest approximation components of blue components of color image on repeat embedding technology while most of other DWT methods embed watermark into the middle or high frequency components. Moreover, two extraction methods can be used to enhance cropping attack. Experimental results show that the proposed algorithm keeps the quality of the image well and is robust enough to JPEG compression, noise , filtering , image scaling, image enhancement, mosaic and cropping etc.