This document discusses various techniques for content-based image retrieval. It begins with an introduction to content-based image retrieval and describes how it uses visual features like color, texture, shape and regions to index and represent image content for retrieval. The document then reviews related work on image retrieval using different features. It discusses features used for image identification like color, edges, corners and texture. The document also outlines techniques for image retrieval including relevance feedback, support vector machines, block truncation coding, and image clustering. Finally, it evaluates parameters for comparing image retrieval algorithms.