Normalizing Multimedia Databases

Multimedia databases have been used in many application fields. As opposed to traditional alphanumeric databases, they need enhanced data models and DBMSs to enable the modeling and management of complex data types. After an initial anarchy, multimedia DBMSs (MMDBMS) have been classified based on standard issues, such as the supported data model, the indexing techniques to support content-based retrieval, the query language, the support for distributed multimedia information management, and the flexibility of their architecture (Narasimhalu, 1996). A conspicuous number of MMDBMS products have been developed. Examples include CORE (Wu, Mehtre, Lam, & Gao, 1995), OVID (Oomoto & Tanaka, 1993), VODAK (Löhr & Rakow, 1995), QBIC (Flickner et al., 1995), ATLAS (Sacks-Davis, Ramamohanarao, Thom, & Zobel, 1995), each providing enhanced support for one or more media domains among text, sound, image, and video. Some of these products support specific data models, whereas others support the object-oriented data model or even the canonical relational data model. Moreover, extensible relational DBMSs have been introduced to extend relational DBMSs with objec-oriented features, such as the capability to manage complex data types, including multimedia data. In particular, they implement the concept of the object-relational universal server, providing means to enable the construction of user defined data types (UDTs), and functions for manipulating them (UDFs). In addition, SQL3 has become the standard for relational DBMSs extended with object-oriented capabilities. The standard includes UDTs, UDFs, LOBs (a variant of BLOBs), and type checking on user-defined data types, which are accessed through SQL statements. Early examples of extensible RDBMSs include Postgres, IBM/DB2 version 5, Informix, and ORACLE 8. As MMDBMSs technology has become more mature, the research community has been seeking new methodologies for multimedia software engineering. Independently from the data model underlying the chosen MMDBMS, multimedia software engineering methodologies should include techniques for database design, embedding guidelines and normal forms to prevent anomalies that might arise while manipulating multimedia data. In this paper, we describe a general-purpose framework to define normal forms in multimedia databases. The framework applies in a seamless way to images as well as to all the other different media types. The semantics of multimedia attributes is defined by means of generalized icons (Chang, 1996), previously used to model multimedia languages in a visual language fashion. In particular, generalized icons are used here to derive extended functional dependencies, which are parameterised upon the similarity measure used to compare multimedia data (Santini & Jain, 1999). Based on these new dependencies, we define three normal forms aiming to reach a suitable partitioning of multimedia data and to derive database schemes that prevent possible manipulation anomalies.