Description of a Single Multimedia Document

ion refers to taking a semantic description of a specific instance of multimedia content (e.g. ‘Alex is shaking hands with Ana’ in the image shown in Figure 8.1) and generalizing it either to multiple instances of multimedia content (media abstraction, e.g. ‘Alex is shaking hands with Ana’ for any picture or video including the images and videos shown in Figure 8.2) or to a set of concrete semantic descriptions (formal abstraction, e.g. ‘Alex is shaking hands with any woman’ or ‘Any man is shaking hands with any woman’). When dealing with the semantics of multimedia content, it becomes necessary to draw upon descriptive techniques such as abstraction because these techniques are part of the way the world is understood and described by humans. MPEG-7 considers two types of abstraction, which are called media abstraction and formal abstraction. Moreover, MPEG-7 also provides ways of representing abstract properties and concepts that do not arise by a media or a formal abstraction. As examples, Figure 8.1 shows a concrete description of an image that contains an abstract property or concept ‘comradeship’ and Figure 8.13 illustrates a media abstraction and a formal abstraction of the description in Figure 8.1. An abstraction, or more precisely, a lambda abstraction, in logic, creates a function from a statement [6]. This process is effected by replacing one or more of the constant expressions in the statement by a variable. There are two types of models for such abstraction, typed and untyped. The more useful method is typed abstraction. For this abstraction, the variable is given a type, such as a data type, and the constants that may be substituted for it must be of this type. In this process, the statement is changed into Alex Ana Concept C1: Label Property Property Semantic relation: Property