Research And Application Of Digital Watermarking Technology In Color Image Archive Protection

With the rapid development of information technology, digital products such as images, audios and videos have been spread widely on the Internet. However, they make the piracy and infringement problems become increasingly serious for their characteristics of accessible and easy to replicate themselves. At present, color images are used widely in people’s daily life and work. Therefore, color image digital watermarking technology has become one of the hot spots in the field of digital watermarking, which makes people pay more and more attention on it. Color image archives are an important form of digital archives. On the one hand, they need to use the robust digital watermarking technology for copyright protection in practice, and on the other hand after extracting the watermarking information they should be able to fully recovery for the characteristics of primitiveness and integrity.According to the characteristics of color image archives, this article is studied from two aspects:the dual color image watermarking technology and reversible watermarking technology. The main research contents are as follows:Firstly, based on the related quaternion theory of color images, this paper proposes a dual color image watermarking algorithm by using quaternion discrete cosine transform (QDCT). It makes full use of the quaternion’s four dimensional space by analyzing the condition of embedding watermarking in the QDCT frequency domain. Then the color watermarking information is embedded into the QDCT real part and imaginary parts of carrier image. When embedding the watermarking, the color watermarking will be preprocessed by QDCT and its frequency domain coefficients will be acted as the watermarking information, which both increases the capacity of the embedding watermarking information and enhances the robustness of the watermarking information. In addition, this paper puts forward a geometric correction method to resist geometric attacks such as rotation, scale and translation, which uses low order quaternions krawtchouk moments as feature vector and adopts the particle swarm optimization-least square support vector marchine (PSO-LSSVM) to get the training model to make geometric correction for the detecting images. At the same time, the algorithm is combined with generalized arnold transform and redundant embedding strategy to improve the robustness of the watermarking. Experimental results show that the proposed algorithm is superior to other algorithms, which makes the watermarking information have better invisibility and robustness.Secondly, based on the reversible watermarking algorithm of multilevel histogram shifting, this paper proposes a reversible watermarking algorithm by using prediction-error histogram shifting technology and the exploiting modification direction (EMD) mechanism. It uses different prediction operators to produce difference histogram in different regions of the host image and embeds the watermarking information by modifying the difference histogram. When embedding watermarking information, at the difference 0 this paper uses the nonary EMD mechanism to improve the watermarking embedding capacity. In addition, the method of preventing overflow and underflow problems is improved, which increases the pure embedded rate. Experimental results show that both for gray image and color image, this paper scheme can achieve high rate of embedded image with better visual quality and performance.Finally, the dual color image watermarking technology and reversible watermarking technology are applied to the integrated archives management system in color image archives protection. That is, embed the robust watermarking into color image archives by using the dual color image watermarking algorithm proposed in this paper. Then the variation of the image embedded region are processed by entropy coding, which will be as the reversible watermarking information. And using the reversible watermarking algorithm proposed in this paper to embed the watermarking into blue proportion of the color image archives. For one thing, our method has good robustness for color watermarking, which is beneficial to copyright protection of the color image archives. For another, using the variation of the embedded region as reversible watermarking information to embed can be used to recovery the original image archives without attacking, which can ensure the primitiveness and completeness of the color image archives.