Research In Geometrical Attack Resistant Digital Watermarking Technology Based On DWT-SVD

With the rapid development of digital communication technology and computer technology, information security of digital products, copyright protection and authenticity recognition issues have become an important concern in today’s world. Digital watermarking technology has good invisibility and robustness, which can be an important way to solve digital multimedia copyright issues. However, today the algorithms can’t effectively resist geometric attacks. It is because the digital watermarking technology in real life applications is limited, which is unable to better balance watermarked image invisibility and robustness.In order to enhance the ability of QR code digital watermark image scan code and the decoding process against geometric attack, this paper presents a digital watermarking technique based on discrete wavelet transform and singular value decomposition. Taking advantage of the multi-resolution features of the Discrete Wavelet Transform and the stability of Singular Value discrete, the watermark is embedded into the low-frequence sub-band LL of the carrier image to making the robustness and invisibility of watermark reaching a certain balance. After the combination of today’s trends and a lot of preparation work myself, I mainly do the following tasks:1. Respectively studying the ability of the discrete wavelet transform(DWT) and singular value decomposition(SVD) against geometric attacks, I proposed a technology against geometric attacks based on discrete wavelet transform and singular value decomposition combining with both the advantages. Compared with the traditional method, the effect of the new technology has significantly improved.2. I designed the algorithm flow chart of the digital watermark embedding and extraction in the process of the watermark against geometric attack. The digital watermark information is embedded into the low- frequency sub-block DWT of the host image making use of singular value decomposition principle, which can maximize the strength of embedded watermark under the condition of guaranteeing without affecting image quality of visual conditions. Experimental results show that the proposed algorithm in the digital watermarking to resist rotation, zoom, pan, etc.(RST) and other geometric attacks has better robustness and invisibility.