Moving Picture Experts Group 7 (MPEG-7) is an international standardization on the architectures of metadata representing multimedia information, such as image, audio and moving picture. An MPEG-7 query format is used to retrieve multimedia contents represented based on the MPEG-7. An MPEG-7 multimedia contents retrieving system retrieves multimedia contents related to a query inputted in an MPEG-7 query format.
The MPEG-7 query format defines syntaxes for retrieving MPEG-7 documents. The syntaxes can represent diverse types of queries that can be used for the retrieval of MPEG-7 documents. For example, they can represent not only natural sentence-type query such as “an image with mountain” but also example-based query using a multimedia file as a query and MPEG-7 textual description-based query.
While representing such diverse queries, referring to the same or different portions of an MPEG-7 document occurs frequently. To be specific, there is a case where more than one retrieval condition should be all satisfied in the same structure. For example, to retrieve moving picture segments with “mountain” and “sea”, the presence of “mountain” and “sea” could be represented for one region. As for joint operation, two different MPEG-7 documents should be referred to. For this, it should be clearly represented that two different documents are referred to.
Conventional MPEG-7 query formats may satisfy more than two retrieval conditions within the same architecture, but they have a shortcoming that they cannot clearly represent reference to two different MPEG-7 documents.