Image Retrieval Based On Feature Watermark

With the development of computer, multimedia and network technologies, the amount of visual information available in the digital format has grown exponentially recently, which has resulted in information explosion and has exceeded the limit of human's acceptability. The introduction of the World Wide Web and the increased memory capacity allow the storage of large amounts of digital data to be possible, especially for huge image databases. Therefore, the need to handle queries and browse in large image databases has become a hotspot. Content-based image retrieval, which uses visual contents to search images from large scale image databases according to users'interests, has been an interesting and rapid developing research field nowdays. Large numbers of papers about image retrieval appears and are applied in several fields.With the deep research on image retrieval, some new problems come after. The development and perfection of network provides convenience to people's life and work. However, it also offers the potential for illegal duplication and manipulation. Therefore, how to make best use of the convenience of network and protect images'copyright simultaneously attracts much attention. Because the object of image retrieval is image information, the above issues are unavoidable. In addition, how to manage huge database during the retrieval process and the storage space are also crucial. In order to solve these problems, researchers began to propose the information hiding technique used in image retrieval. Digital watermarking technology is considered as an alternative tool for protecting these intellectual properties. It attempts to embed copyright and authentication codes within media content to identify the true owner and authenticate the digital information. Based upon such a background, our paper proposes image retrieval based on feature watermark.We present different multipurpose watermarking schemes in different applications fields: image retrieval and copyright protection (robust watermark); image retrieval and copyright notification (visible watermark); image retrieval and content integrity verification (fragile watermark). Our retrieval system consists of two main phases, the offline process and the online retrieval process.