document.106

Semantic representation of multimedia information is vital
for enabling the kind of multimedia search capabilities that professional
searchers require. Manual annotation is often not possible
because of the
shear scale of the multimedia information that needs indexing. This paper explores the ways in which we are using both top-down, ontologically
driven approaches and bottom-up, automatic-annotation approaches to
provide retrieval facilities to users. We also discuss many of the current techniques that we are investigating to combine these top-down and
bottom-up approaches.
1 Introduction
The hallmark of a good retrieval system is its ability to respond to a user’s queries
and present results in a desired fashion. In the past there has been a tendency
for research to focus on content-based retrieval techniques, ignoring the issues of
users. In spite of this, some investigators have attempted to characterise image
queries, providing insights in retrieval system design [1,
2, 3, 4] and highlighting
the problem of what has become known as the
semantic gap.
In the survey of content-based image retrieval by Smeulders
et al. [5], the
semantic gap is described as;
...the lack of coincidence between the information that one
can extract
from the visual data and the interpretation that the same dat
a have for
a user in a given situation.