Visual image retrieval: seeking the alliance of concept-based and content-based paradigms

In the commercial use of picture collections, a heavy dependency continues to be exhibited on a concept-based image retrieval paradigm in which the query is verbalised by the client and resolved as a metadata text-matching operation. The practical and philosophical challenges posed by the indexing aspect of image metadata construction are significant and frequently expressed. Nevertheless, it has taken image digitisation to bring this particular information retrieval problem to prominence in the research agenda. Metamorphosed into a binary data structure, the digital image offers some enticing processing opportunities which content-based image retrieval techniques are exploiting with developing success. Drawing on studies of user need, this paper seeks to explain why a heavy dependency will continue to be placed on concept-based rather than content-based image retrieval techniques within archival image collections. In contrast, the promising nature of content-based techniques from the viewpoint of a growing clientele with less traditional visual information needs will also be considered. The paper concludes by offering the view that, while both concept-based and content-based approaches suffer from operational limitations, the further development of a hybrid image retrieval paradigm which combines the two approaches makes a potentially valuable contribution to the research agenda for visual image retrieval.