With recent advances in multimedia technology, on-line libraries of digital images are assuming an ever increasing relevance within a wide range of information systems. Effective access to these archives requires not only conventional searching techniques based on keywords, but also content-based queries which allow visual features of data to be searched. This new comprehensive reference introduces the intricate science of implementing image modeling and retrieval based on the shape, on the color and texture, or on the spatial arrangement of imaged objects. Building on this introduction, six chapters by major research groups in the field detail and compare different modeling approaches.