This book covers the state of the art in image indexing and retrieval techniques paying particular attention in recent trends and applications. It presents the basic notions and tools of content-based image description and retrieval, covering all significant aspects of image preprocessing, features extraction, similarity matching and evaluation methods. Particular emphasis is given in recent computational intelligence techniques for producing compact content based descriptors comprising color, texture and spatial distribution information. Early and late fusion techniques are aslo used for improving retrieval results from large probably distributed inhomogenous databases. The book reports on the basic international standards and provides an updated presentation of the current retrieval systems. Numerous utilities and technques are implemented in software, which is provided as a supplementary material under an open-source licence aggreement. The book is particularly useful for postgraduate students and researchers in the field of image retrieval, who want to easlily elaborate and test state of the art techniques and possibly incorporate it in their development.