The Research For Zero-Watermarking On Two-Dimensional Engineering Graphic

Digital watermarking technology on two-dimensinal engineering graphic involves cryptography, image processing, information security and other cross-disciplinary researches. It is a new research direction in digital watermarking field. At present, the watermark in two-dimensional engineering drawings has many limitations, such as small capacity, poor robustness and low accuracy.In order to solve these problems, this paper presents zero-watermarking research on the two-dimensional engineering drawings. First, this paper presents the background, feature, classification and current research status of the two-dimensional engineering graphic watermarking, followed by analyzing the shortcomings in the existing watermarking. And then, the relevant theoretical knowledge, including Chaos Theory, Best tree, Search tree, Wavelet Transform, and their respective features are introduced. Finally, two watermarking schemes are proposed: one is a robust watermark which is used for copyright protection. To enhance this watermark's robustness and security, the method uses the vertexes values which has high probability of having same value to generate the watermark, and uses the chaotic system which is highly sensitive to initial value to enhance the wartermark's secrecy. Experimental results show that the algorithm is robust against some processing operations such as even scaling, translation, adding, deleting. The other is a kind of fragile zero watermark which is used for content authentication. This method uses the entities'topological and handles'values to generate the zero-watermark. Experimentations show that the watermark is robust to these processing operations which do not change the content of the original graphic, such as translation, even scaling, rotate; it is sensitive to the processing operations which changes the content of the original graphic, such as deleting, adding, local translation. The algorithm can orientate the modified entities.