The Digital Watermarking Research And Application Based On Smart Phone Platform

With the popularity of the Internet and the rapid development of multimedia processing technology,multimedia information sharing has become a popular topic in the network age. but it is a phenomenon that the security of the digital information faces serious challenges. So multimedia copyright protection and content authentication has increasingly become very important and challenging research topics. In such a case, the digital watermarking technology comes into being and becomes an efficient way of complementing the security leaks of traditional encryption protecting scheme. It is used for identification, distinguishing and hiding information with the data redundancy in the multimedia. And it embeds the secret information into them. This technology has been widely applied in many kinds of digital products such as the image, voice, video and other digital products. So it has become a popular topic in multimedia information security field. At the same time,the widespread popularity of smartphone and the promotion of 3G communication makes mobile phone becaming one of the most convenient and efficient ways to obtain multimedia information. Therefore, the research of digital watermarking algorithm for smartphone platform application has promising prospects and practical significance.With the digital watermarking technology, we do the research on mobile imaging technology deep for the application of smartphone. And we design and implement an image authentication system for Windows Mobile platform with the improved semi-fragile color image digital watermarking algorithm based on DCT. The system can provide mobile users with the scientific support to distinguish the authenticity and reliability of digital images. Besides, it also has some research significance and potential commercial value.In this thesis,in the first place,we introduce the basic theory of digital watermarking, the basic characteristics, application areas and the classification of digital watermarking. Then we summarize of the evaluation criteria of the digital watermarking imperceptibility and robustness, especially for some typical algorithm of the digital watermarking.Secondly, taking the character of smartphone platform into consideration,In order to the system has advantages on the space of phone storage and improvement of image transmission rate,we regard the color images of JPEG as our importance and proposed an improved semi-fragile color image digital watermarking algorithm based on DCT. In the process of watermark embedding, we have an adequate consideration on the characteristics of Human Visual System,around the invisibility and robustness of watermark,we optimize the space of watermark's embedding and improve Watermark's embedding way based on the following theory, such as Discrete cosine transform, image edge feature, static image compression coding. In addition,in order to enhance the security of the watermark, we transform watermark images with Arnold. And the extraction of the watermark is blind extraction. In another word, it dose not need original images.Experimental results show that the algorithm not only has higher image quality, but also has good resistance to JPEG compression performance and high sensibility of malicious tampering. Hence, we combine the research with the needs of the system to suit the application of realistic meaning.Finally,in-depth research of solution to smartphone image acquisition technology make use of DirectShow for Windows Mobile platform, and base on the system requirements analysis, we design and implement an image authentication system of application for smartphone. And the system is based on C/S architecture and makes use of the combination of semi-fragile color image digital watermarking algorithm based on DCT and the smartphone platform of Windows Mobile.