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 des