As a result of the new communication technologies and the massive use of Internet in our society, the amount of audio-visual information available in digital format is increasing considerably.
Therefore, it has been necessary to design some systems that allow us to describe the content of several types of multimedia information in order to search and classify them.
These descriptors have a good knowledge of the objects and events found in a video, image or audio and they allow the quick and efficient searches of the audio-visual content.
The description of the audio-visual content is not a superficial task and it is essential for the effective use of this type of archives.
The standardization system that deals with audio-visual descriptors is the MPEG-7 (Motion Picture Expert Group - 7).
The set of descriptors is formed by: It contains important semantic information due to human's ability to recognize objects through their shape.