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Friday, August 14, 2009

Introduction to Multimedia Databases

Multimedia data typically means digital images, audio, video, animation and graphics together with text data. The acquisition, generation, storage and processing of multimedia data in computers and transmission over networks have grown tremendously in the recent past. Multimedia data are blessed with a number of exciting features. They can provide more effective dissemination of information in science, engineering , medicine, modern biology, and social sciences. It also facilitates the development of new paradigms in distance learning, and interactive personal and group entertainment. It loosely fall into three main categories:
* Static media (time-independent, i.e. images and handwriting).
* Dynamic media (time-dependent, i.e. video and sound bytes).
* Dimensional media (i.e. 3D games or computer-aided drafting programs- CAD).

There are numerous different types of multimedia databases :
* The Authentication Multimedia Database (also known as a Verification Multimedia Database, i.e. retina scanning), is a 1:1 data comparison.
* The Identification Multimedia Database is a data comparison of one-to-many (i.e. passwords and personal identification numbers.
* A newly-emerging type of multimedia database, is the Biometrics Multimedia Database; which specializes in automatic human verification based on the algorithms of their behavioral or physiological profile.

A multimedia database needs to manage several different types of information pertaining to the actual multimedia data. They are:
* Media data - This is the actual data representing images, audio, video that are captured, digitized, processes, compressed and stored.
* Media format data - This contains information pertaining to the format of the media data after it goes through the acquisition, processing, and encoding phases. For instance, this consists of information such as the sampling rate, resolution, frame rate, encoding scheme etc.
* Media keyword data - This contains the keyword descriptions, usually relating to the generation of the media data. For example, for a video, this might include the date, time, and place of recording , the person who recorded, the scene that is recorded, etc This is also called as content descriptive data.
* Media feature data - This contains the features derived from the media data. A feature characterizes the media contents. For example, this could contain information about the distribution of colors, the kinds of textures and the different shapes present in an image. This is also referred to as content dependent data.

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