The human–machine interface is evolving at an incredible pace, surpassing the traditional text-based boundaries. A driving force motivating this development is the need to endow computers with capabilities that parallel our perceptual abilities. Vision is arguably our most significant sense, giving rise to efforts to empower computers to represent, process, understand, and act on visual imagery. As a result, images are being generated at a mind-boggling pace from a variety of sources. | Image Databases Search and Retrieval of Digital Imagery Edited by Vittorio Castelli Lawrence D. Bergman Copyright 2002 John Wiley Sons Inc. ISBNs 0-471-32116-8 Hardback 0-471-22463-4 Electronic 13 Shape Representation for Image Retrieval BENJAMIN B. KIMIA Brown University Providence Rhode Island INTRODUCTION The human-machine interface is evolving at an incredible pace surpassing the traditional text-based boundaries. A driving force motivating this development is the need to endow computers with capabilities that parallel our perceptual abilities. Vision is arguably our most significant sense giving rise to efforts to empower computers to represent process understand and act on visual imagery. As a result images are being generated at a mind-boggling pace from a variety of sources. Terabytes of data are being generated in the form of aerial imagery surveillance images mug shots fingerprints trademarks and logos graphic illustrations engineering line drawings documents manuals medical images images from sports events documentation of environmental resources in the form of images and entertainment industry photos and videos 1-7 . Clearly the management of such databases must rely on the perceptual and cognitive dimensions of the visual space namely color texture shape and so on. The basic premise is that there exists qualitative aspects of images that can be used to retrieve images without fully specifying them. The use of shape as a cue is less developed than the use of color or texture mainly because of the inherent complexity of representing it. Yet retrieval-by-shape has the potential of being the most effective search technique in many application fields. This chapter reviews and discusses the representation of shape as a cue for indexing image databases. The central question is how complete or partial information regarding a shape in an image can be represented so that it can be easily extracted matched and retrieved. Specifically five key items must be .
