MPEG-7 will define a certain set of descriptors to describe these features. For example, the color histogram can be a very suitable descriptor for color characteristics of an image, and motion vectors (commonly available in compressed video bitstreams) form a useful descriptor for motion characteristics of a video clip. MPEG-7 also uses the concept of description scheme (DS), which means a framework that defines the descriptors and their relationships. Hence, the descriptors are the basis of a description scheme. Description then implies an instantiation of a description scheme. MPEG-7 not only wants to standardize the description, but it also. | FIGURE The scope of MPEG-7. motion are example features that are desirable in many applications. MPEG-7 will define a certain set of descriptors to describe these features. For example the color histogram can be a very suitable descriptor for color characteristics of an image and motion vectors commonly available in compressed video bitstreams form a useful descriptor for motion characteristics of a video clip. MPEG-7 also uses the concept of description scheme DS which means a framework that defines the descriptors and their relationships. Hence the descriptors are the basis of a description scheme. Description then implies an instantiation of a description scheme. MPEG-7 not only wants to standardize the description but it also wants the description to be efficient. Therefore MPEG-7 also considers compression techniques to turn descriptions into coded descriptions. Compression reduces the amount of data that need to be stored or processed. Finally MPEG-7 will define a description definition language DDL that can be used to define modify or combine descriptors and description schemes. Summarizing MPEG-7 will standardize a set of descriptors and DSs a DDL and methods for coding the descriptions. Figure illustrates the relationship between these concepts in MPEG-7. FIGURE Relationship between elements in MPEG-7. The process to define MPEG-7 is similar to that of the previous MPEG standards. Since 1996 the group has been working on defining and refining the requirements of MPEG-7 . what MPEG-7 should provide . The MPEG-7 process includes a competitive phase followed 2001 CRC Press LLC by a collaborative phase. During the competitive phase a call for proposals is issued and participants respond by both submitting written proposals and demonstrating the proposed techniques. Experts then evaluate the proposals to determine the strength and weakness of each. During the collaborative phase MPEG-7 will evolve as a series of experimentation models XMs where .
