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The decreasing costs of consumer electronic devices such as digital cameras and digital camcorders,
along with the ease of transportation facilitated by the Internet, has lead to a phenomenal rise in the
amount of multimedia data. Now multimedia data comprising of images, audio, and video is becoming
increasingly common. Given that this trend of increased use of multimedia data is likely to accelerate,
there is an urgent need for providing a clear means of capturing, storing, indexing, retrieving, analyzing,
and summarizing such data.
Image data, for example, is a very commonly used multimedia data. The early image retrieval systems
are based on manually annotated descriptions, called text-based image retrieval (TBIR). TBIR
is a great leap forward, but has several inherent drawbacks. First, textual description is not capable of
capturing the visual contents of an image accurately, and in many circumstances, textual annotations are
not available. Second, different people may describe the content of an image in different ways, which
limits the recall performance of textual-based image retrieval systems. Third, for some images there is
something that no words can convey. To resolve these problems, content-based image retrieval (CBIR)
systems are designed to support image retrieval, and have been used since the early 1990s. Also, some
novel approaches (e.g., relevance feedback, semantic understanding, semantic annotation, and semantic
retrieval of images) have been developed in the last decade to improve image retrieval and satisfy the
advanced requirements of image retrieval.
Multimedia data retrieval is closely related to multimedia data management. Multimedia data
management facilitates the manipulation of multimedia data such as representation, storage, index, retrieval,
maintenance, and so on. Multimedia data retrieval is the key to implementing multimedia data
management on one hand. On the other hand, multimedia data retrieval should be carried out based
on multimedia data representation, storage, and index, which are the major tasks of multimedia data
management. Databases are designed to support the data storage, processing, and retrieval activities
related to data management, and database management systems can provide efficient task support and
tremendous gain in productivity is hereby accomplished using these technologies. There is no doubt that
database systems play an important role in multimedia data management, and multimedia data management
requires database technique support. Multimedia databases, which have become the repositories
of large volumes of multimedia data, are emerging. |