#description based retrieval

Multimedia

Includes:  images, audio, video, animation, interactivity, etc. 

These types of files are difficult to retrieve because of their innate nature primarily non-text based content.  Search engines typically use keywords to retrieve files, but that would not work on these types of media because the keyword search cannot process information that is not text.  This lead to two different types of approaches being created to be able to retrieve multimedia files.  

Description Based Retrieval vs. Content Based Retrieval of Still Images

The description based approach is reliant upon outside sources for descriptions of the file.  This includes the file's physical attributes and subject attributes.  This information is more commonly known as metadata.  This gives the file keywords for the search engine to find.  

The content based approach gets its description of the file from the contents of the file.  The color, shape, and texture are used to describe the file for the search engines to be able to find it.  

TREC