| Summary: | 博士 === 國立交通大學 === 電子工程系所 === 94 === With the advances in multimedia, communication, and consumer electronics technologies, a vast amount of digital contents are produced by almost everyone every day. In this study, we investigate two challenging topics in the digital content management area. The first one is the content-based image search, and the second is the layered content protection.
The content-based image search has long been considered a difficult task. Making correct conjectures on the user intention (perception) based on the query images is a critical step in the content-based search. One key concept of our proposed algorithm is how we find the user preferred low-level image characteristics from the multiple positive samples provided by the user. The second key concept is how we use negative images as a pruning criterion. The third key concept is how we generate a set of consistent "pseudo images" when the user-provided samples are insufficient. The notion of image feature stability is thus introduced. In realizing the preceding concepts, an image search scheme is developed using the weighted low-level image features. At the end, quantitative simulation results are used to show the effectiveness of these concepts.
The second topic in this thesis is content protection. Intellectual Property (IP) protection is a critical element in multimedia transmission and delivery systems. Conventional IP protection on multimedia data can be categorized into encryption and watermarking. In this study, by combining encryption and robust watermarking, a structure that performs layered access control on scalable media is proposed, implemented, and verified. Taking the advantages of both encryption and watermarking, we can securely protect copyrights of multimedia contents and provide multiple-grade services at the same time. In the summated examples, we simulate two scalable transmission schemes over a broadcasting environment and use them to test the effectiveness and feasibility of the proposed method. When the embedded watermark is extracted with high confidence, the key to used decrypt the next layer can be perfectly recovered. Then, the media contents are reconstructed and the copyrights are assured.
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