This book constitutes the refereed proceedings of the International Workshop on Multimedia Content Representation, Classification and Security, MRCS 2006, held in Istanbul, Turkey in September 2006.

The 100 revised papers presented together with 4 invited lectures were carefully reviewed and selected from more than 190 submissions. The papers are organized in topical sections on biometric recognition, multimedia content security, steganography, watermarking, authentication, classification for biometric recognition, digital watermarking, content analysis and representation, 3D object retrieval and classification, representation, analysis and retrieval in cultural heritage, content representation, indexing and retrieval, content analysis and classification, feature extraction and classification, multimodal signal processing, 3D video and free viewpoint video, multimedia content transmission and classification, video and image processing, as well as video analysis and representation.