Multimedia data such as audios, images, and videos are semantically richer
than standard alphanumeric data. Because of the nature of images as combina
tions of objects, content-based image retrieval should allow users to query
by image objects with finer granularity than a whole image. In this paper,
we address a web-based object-based image retrieval (OBIR) system. Its pro
totype implementation particularly explores image indexing and retrieval us
ing object-based point feature maps. An important contribution of this work
is its ability to allow a user to easily incorporate both low- and high-le
vel semantics into an image query. This is accomplished through the inclusi
on of the spatial distribution of point-based image object features, the sp
atial distribution of the image objects themselves, and image object class
identifiers. We introduce a generic image model, give our ideas on how to r
epresent the low- and high-level semantics of an image object, discuss our
notion of image object similarity, and define four types of image queries s
upported by the OBIR system. We also propose an application of our approach
to neurological surgery training. (C) 2000 Academic Press.