Digital Watermarking Algorithm Of JPEG Image Based On DCT Domain

With the rapid development of computer and network technology,the content industry of internet large platform has become a new platform for human information dissemination and sharing,the virtual nature and freedom of internet communication have led to the low cost and uncontrolled copyright infringement of Internet,and the infringement of piracy has been repeated,aiming at the protection of digital copyright.Therefore,the main content of the paper is a simple introduction to the development history and process of digital watermarking,and then combined with domestic and foreign watermarking technology to summarize the current research situation,the related technology has made a detailed overview.Combining the digital correlation technology and the author's research direction,this paper analyzes the international compression standard of JPEG image and the technical characteristics of DCT,and puts forward three kinds of algorithms based on the digital watermarking of JPEG image in DCT domain.First,in order to solve the problem of poor robustness of some digital watermarking algorithms under different types of attack,a dual digital watermarking algorithm based on discrete cosine transform and singular value decomposition is proposed.Firstly,the watermark information will be embedded in a certain rule to generate another watermark information by pixel permutation.Secondly,the JPEG image is the 8x8 block DCT transform,the DC coefficient and the second low frequency coefficient of each block are chosen to generate two coefficients matrix,then SVD decomposition,and then two watermark information is embedded in the singular value matrix of two matrices respectively.The experimental results show that the watermark embedded in the DC coefficients and the adjacent low-frequency coefficients has good invisibility,and has strong robustness to the JEPG compression,median filtering,salt and pepper noise,and large area shearing attack.Second,aiming at some existing robust watermarking algorithms with high BER and no image authentication function,this paper presents a watermarking algorithm based on discrete cosine transform(DCT),error correcting code and recoverable digital signature.The algorithm uses digital signature with message recovery and Reed-solomon error-correcting code to generate watermark information,then transforms the vector image into block DCT,selects each block if region,and embeds the watermark according to certain rules.The experimental results show that the algorithm has strong robustness against common attacks such as JPEG lossy compression,noise and filtering.The digital signature scheme with message recovery is used to extract the experience of water-printed information and achieve the purpose of watermark image authentication.Thirdly,Third,a DCT robust watermarking algorithm combined with JPEG image compression coding is proposed,which refers to the multi-stage DCT transform into the algorithm,first carries the image to the 8x8 block,then implements the first discrete cosine transform,after the Zig-zag sorting,will be the former 4x4 coefficient value two times for DCT transformation,The DC coefficients of two transformations are obtained,the new matrix of each DC coefficient is extracted,and the singular value decomposition of the matrix is combined,and the singularity of the coefficient matrix and watermark information is decomposed to realize the embedding of watermark.By studying the international JPEG image compression Standard,the author realizes three kinds of digital watermarking algorithms based on DCT domain,and evaluates the performance of these three algorithms by simulation experiment.Experimental results show that the first algorithm proposed by the author shows good robustness in resisting JPEG compression,common noise/filtering and other attacks,and also ensures good invisible lines under different embedding intensities.The second algorithm can extract the effluent printing information completely and correctly in response to some common non-malicious attacks,and ensure the strong authentication of the watermark image.Algorithm three is verified by experimental data,which has strong robustness compared with a digital watermarking algorithm based on DCT transform.