Research On Technique Of Digital Image Watermarking Based On Wavelet Transform

As the rapid development and wide application of multimedia and network technologies,the storage,processing and transmission of digital multimedia products is becoming much more convenient and faster.In this situation,how to prevent the digital products from infringing,pirating and tampering has become a hot topic to deal with.As a result,digital watermarking technology emerges and develops to an essential subject,which makes international academe focus on. This dissertation studies some related technologies of digital image watermarking based on wavelet transform.The paper introduces the developing status quo,basis models,attributes classifications,and applications of digital image watermarking technology; Systematically discuss each module design,performance evaluation and attacking ways;explains the relative theories of image wavelet decomposition and then concentrates on analyzing embedded areas and the selection of wavelet function. On the basis of these analyses,make use of discrete wavelet transformation (DWT),chaotic mapping,etc.to design digital image watermarking.For two application areas of digital images-the copyright protection and integrality authentication,this paper proposes three watermarking schemes based on discrete wavelet transformation.The first one is a wavelet-based semi-fragile watermarking scheme,with ability to detect,locate and self-recover minor tamper applied to the watermarked image,whose main characteristic is being able to restore the altered or destroyed regions of the attacked images.The second one is semi-fragile watermarking scheme based on integer wavelet transform,which uses a novel strategy-modifying neighboring coefficients in the block of intermediate frequency sub-band-to embed the watermark signal to host image. The third one is an improved digital image watermarking based on SVD-DWT, according to analyzing the drawbacks of a sort of SVD based watermarking algorithms.All the three schemes apply chaotic sequence to permute the watermark information in advance.Through a lot of emulation experiments,validate and analyze the performances of the proposed schemes.The experimental results show that these three proposed algorithms have favorable performances and be applicable to the design of different watermarking systems.