Vector Graphics Reversible Watermarking System Design

The rapid development of computer networks and communication technology islike a double-edged sword, which brings both the wide usage of multimedia technologyand security risks. As a new copyright protection technology, digital watermarkingtechnology came into being. It can be implemented in the open network environmentfor copyright protection and integrity verification, and becomes a hot research topic inthe copyright protection field.The majority of digital watermarking research is in the field of image, includingthe fragile watermarking technology for integrity verification and the robustwatermarking for copyright protection. With the maturity of digital watermarkingtechnology and wide usage of vector graphics, digital watermarking technology is nolonger limited to images. Graphics watermarking technology for CAD graphics and GISmaps begins to appear, and gradually becomes the emerging hot spots in the field ofdigital watermarking.This thesis first introduces the background of the development of digitalwatermarking technology, including its history, the main results achieved, the field ofapplication and the characteristics of digital watermarking. By analyzing andsummarizing the characteristics of the existing watermarking algorithms for graphicsand images of various algorithms, the thesis does some new research on CAD graphics.The main works are as follows:1. A new digital watermarking algorithm for CAD graphics is proposed. Thealgorithm uses the ratio of the Euclidean distance between the element verticesas watermark carriers and divides the quantify results into the quotient sets andremainder sets. The watermark is embedded into remainder sets. Thisalgorithm has a high capacity.Since the ratio of data is used as the carrier, thealgorithm has good robustness and can effectively resist the translation,rotation and scaling attacks.2. Based on the watermarking algorithm for CAD graphics, by combining withthe software engineering knowledge, a system is designed to integrates thefunctions of watermark embedding, watermark extraction, the tamperdetection and document authentication. By following the theory of designpatterns, the system has good scalability, so that other watermarking algorithms for different watermark carriers can be added to the system easily.The proposed algorithm and the designed system can be apply to enhance theSecurity of CAD graphics.