Research On Digital Watermarking Algorithm For Color Image And Its Application

With the high-speed development of the Internet and the rapid popularization of network,the number of digital products which as the carrier on the network is increasing.The digital information on the Internet which in the process of transmission and exchange are frequently stolen,tampered and disseminated by some individuals and organizations in the absence of any authorization,which is a serious threat to network security.Digital watermarking technology can effectively solve the above problems,and it plays an important role in many fields,such as copyright protection and information security.Currently,how to enhance the robustness of digital watermarking has become a hot topic in this field.In addition,the era of paperless office has arrived.Electronic seal as an important part of e-commerce,its copyright protection and information security have become an issue of much concern.The background and importance of the research contents are expounded by the thesis,as well as the digital watermarking algorithms.After the color digital watermarking algorithms are studied deeply,a digital watermarking algorithm based on block and NSCT-SVD is proposed.Meanwhile,the digital watermarking algorithms applied to electronic-seal are analyzed.Afterwards,a color digital watermarking algorithm for electronic-seal is proposed.And based on the idea of object-oriented software design method,a prototype system of digital watermarking for electronic-seal is designed and realized.The main work can be summarized as follows:(1)An algorithm based on block and NSCT-SVD for digital watermarking is proposed.The three channels(R,G,B)of cover image are all divided into four non-overlapping blocks,then apply NSCT to each block to obtain corresponding low frequency sub-band information.Then apply SVD to those sub-band information and the three channels(R,G,B)of watermarking image.Considering the principle that the robustness and the invisibility of watermark must be better balanced,the watermark embedding factor is optimized,then the singular values of the three channels of watermark information are added to the singular values of the low frequency sub-band information of each block in the corresponding channel of the original image,and the color image digital watermark embedding is realized.Experimental results show that this algorithm has good invisibility and robustness to resist all kinds of attacks,suchas noise,geometric attacks,filtering,and so on.(2)An algorithm based on Arnold scrambling and DWT-BSVD for digital watermarking is proposed,which is suitable for electronic-seal with fixed structure and single color.First of all,the three channels(R,G,B)of the original electronic-seal are respectively processed by the two level DWT transform to transform them into four sub-bands.Then apply BSVD to those sub-bands and scrambling watermark by Arnold to obtain the corresponding bidiagonal singular value.Finally,the watermark is embedded to the electronic-seal by adding bidiagonal singular value.The experimental results show that the proposed algorithm has good invisibility and robustness compared with other digital watermarking algorithms,which is better suitable for electronic-seal.(3)According to the issues of the copyright protection and security in electronic-seal printing industry,based on the requirement of JiangSu Start Dima Data Processing Co.,Ltd.,an electronic-seal color digital watermarking system is designed and developed using Object-Oriented.The system is practical and easy to operate.It not only provides the function of watermark embedding and detection for electronic-seal cover image,but also has good invisibility and robustness.