Research And Realization Of Watermarking Technology Based On The Vector Engineering Drawing

With the rapid development of the internet, various kinds of digital multimedia information have widely distributed through network such as text, image, audio and video etc. But the information on internet can be easily duplicated and modified. So the copyright infringing problem on internet is becoming more and more serious. How to provide copyright protection has drawn extensive attention in recent years. To solve this problem the digital watermarking technique has been investigated. Because of it, the engineering drawing is extensively applied, and challenges the copyright protection of the engineering drawing as well. The digital watermarking technology is an available tool to solve these problems. Especially the research on digital watermarking that focused on two-dimensional vector graphics is becoming hotspot.Digital watermarking technique, which embeds special information into digital products, is a new method for copyright protection with the help of digital watermark, we can prove the originator's owner to digital products that he creates, and the watermark can be the proof of authentication and prosecuting illegal copyright infringing. Basically, there are two common methods of digital watermarking technique: spatial domain methods and transform domain methods. Spatial domain techniques are easy ways to embed information, but they are highly vulnerable to even small cover modifications. In many cases even the small changes resulting out of loss compression systems yield to total information loss. Transform domain methods hide watermark in significant areas of the host image that makes them more robust to attacks, such as compression, cropping, and some other image processing, than the spatial methods. In fact, these kinds of algorithms are not only robust to various kinds of signal processing but also remain imperceptible to human sensory system. There are two main transform domain methods, one is to use the discrete cosine transform (DCT), and the other is the use of discrete wavelet transform (DWT).A new concept,"statistics watermarking", is introduced and instanced in this thesis. The algorithm withdraws the vertices of lines coordinates from the original drawing which is generated into some sequences from the two-dimensional vector graphics. Then the sequences are transformed into different spatial and frequency coefficients through discrete wavelet transform. The algorithm embeds the watermarks into the two-dimensional vector graphics by modifying the wavelet magnitude coefficients. While detecting it is compared with data of tested drawing to evaluate the correlation coefficient, on which a judgment of watermarking existence will be made. Experiments verify the robustness of this approach.The major research works and innovatory points in this thesis are as follows:1. Investigate the basic principles and characteristic of digital watermarking technique,introduce the research backgrounds, basic principles, application areas, and recent development and the future of the digital watermarking technology.2. State of art watermarking technologies for vector drawing. The basic concepts, the category methods, the representative algorithms and the attacking measures of vector drawing watermarking schemes were briefed. This paper summarizes presently the research of watermarking algorithm based on vector graphics, analyses the characteristic on expressing and using of date, the Requirement that embedded digital watermarking into vector graphics, the type of redundant information etc. And introduces typical algorithms aimed at varies of classification methods.3. Analyze the algorithm of Mallet and the concept, characteristic of wavelet transform which includes the continuous wavelet transform and the discrete wavelet transform, point out the advantages of using wavelet transform in digital watermarking and mufti-resolution analysis. In addition, the problems which emerge in this application are explained in a great detail in this paper.4. The pre-processing technique of watermarking is studied, especially the Arnold transformation and the transformation period of 2D Arnold under different number is reached.5. This thesis aims at the characteristics of two-dimensional vector graphics and proposes the advanced statistics techniques which served in the two-dimensional vector graphics are introduced into watermarking algorithm based on DWT(discrete wavelet transform). The important find of engineering drawing is figured out by comparing characteristic, express form and storage structure, there are line-objects. With analysis all coordinate in order to find the best position of watermark embedding. Based on this, a new meaningful digital watermarking algorithm on DWT for 2D drawing is presented. Making use of masking peculiarity of system, before embedding, the watermark picture is processed, which is to enhance the robustness of the watermark. The algorithm withdraws the vertices of lines coordinates which are generated into some sequences from the two-dimensional vector graphics. Then the sequences are transformed into different spatial and frequency coefficients through discrete wavelet transform. The algorithm embeds the watermarks into the two-dimensional vector graphics by modifying the wavelet magnitude coefficients. And lots of experiments have shown the good imperceptibility and robustness under the attacks.At last, this thesis points out still existing problems of two-dimensional vector graphics watermarking technology and proposes the possible directions and emphases that could arise in the future.