Watermark Techniques Of 2-dimension Vector Drawings

Digital watermarking technology is an important direction in the research of information hiding technology, which has significant value in the content authentication and copyright protection of the multimedia such as digital images. The convenience of the Internet and the low-cost of the copying of the digital media, that promote digital products in the real world application of the rapid development, has also brought a series of challenges. However, the non-controlled digital information dissemination makes digital media copyright protection and authentication issues become of concern, while the digital watermarking technology is an effective means to solve this problem. Among the various of digital media products, 2-D vector drawings are widely used in the areas such as construction, military and medicine, and they are more specific and more pratical than normal digital images, so they have a higher economic value. Therefore, the security needs of the 2-D vector drawings become more urgent, and the digital watermarking technology for the 2-D vector drawings comes into being. In this paper, a research of reversible watermarking and tampering locating watermarking are being done in the needs of the variaty of areas.This paper first presents a grid-based division of fragile watermarking algorithm. The algorithm scans the original drawing and devide it into a large number of adaptive grid; then by using the topological invariants of vector drawings and vertex exchange method, we embed the hash of the data in each grid in the grid itself. This method changes the traditional ways that should change the cordinate of the drawing. Meanwhile, this algorithm has the characteristics that can locate the tempering, and has a better concealment and a wider range of adaptability.Then, this paper focuses on the research of the revisible watermarking algorithm of 2-D vector drawings. We embed the watermark in the adjacent points in the drawing using the method of integer transform. This algorithm embed the watermark in the drawing itself and can fully restore the drawing when the watermark is extracted. In the same time, the algorithm will not cause a big disturbance and affect the normal use of the drawing, with considerable practicality. Finally, for the needs of CAD software document security protection system, a multi-watermarking technology is rised and appied in the system. It has an important significance in the using of 2-D drawing for secure storage.