Digital Image Watermark Algorithm Research By Combining DWT And SVD

The digital watermarking is an important means to provide the copyrightprotection,information security, therefore the research of secure and robust digitalwatermarking technique is still challenging research, also remains a popular applicationforeground.It is important to study more secure and robust watermark in this paper. Firstly,this paper put forwards an image encryption algorithm based on chaotic binarysequences, which has well effect to encrypt watermark picture. Secondly, we presenttwo hybrid scheme based on the Discrete Wavelet Transform(DWT) and Singular ValueDecomposition(SVD) by means of the analysis of features of wavelet sub-blockssingular value and influence degree between the commonly used image processingtechnique and noise interference.1) Based on the algorithm of DWT-SVD robust watermark image embedding andextracting.Decomposing the cover image into four bands, we apply the SVD to each band,and embed the same watermark data by modifying the singular values. Modification inall frequencies allows the development of a watermarking scheme that is robust to awide range of attacks. We observed that the scaling factor can be chosen from a fairlywide range of values for LL, and also for the other three bands, the scaling factor can bechosen according to the relation of maxim singular value coefficient betweensub-blocks and watermark. Experiment results show that the algorithm can resist allkinds of classical attacks, specially, the strong robustness for anti-compound attacks.2) Robust blind watermarking algorithm based on DWT-SVDDWT-SVD domain watermarking is put forward by the picture PSNR analysis andquantization watermark's error analysis, we can determine the best energy or capacity tobe added to the original image. Experiments and attacks test show that the algorithm hasgood robustness.In order to ensure the security of the watermark system, this paper gives an imageencryption algorithm based on chaotic binary sequences, also improves algorithm ofgray distance to evaluate the effect of binary image encryption. By experimenting onchaotic sequence sensitivity on their initial condition, the scrambling of distance pixels,and the encrypting and de-encrypting speed of images, the result shows that theencryption algorithm effect is good and low computational complexity and highsecurity.Finally, based on the proposed scheme and Microsoft Visual C++ 6.0 environment,we have designed a corresponding software system for watermark embedding,watermark extracting, image encryption, de-encrypting and watarmark robustness detecting, etc.