Semantic indexing in image retrieval using description logic

We study the use of description logic for semantic indexing in image retrieval systems in order to bridge the gap between low-level features extracted with image analysis and the complex structure of objects. In our approach, starting from a region based segmentation of images, we extract shape, color, position, size and rotation features and provide a syntax for the description of complex objects as composition of simpler "basic" shapes. An extensional semantics allows to define reasoning services, such as recognition and subsumption. A simple user interface allows to describe prototypical images and pose structured queries by sketch.