This book constitutes the refereed proceedings of the 8th International Workshop, IWDW 2009, held in Guildford, Surrey, UK, August 24-26, 2009.The 25 revised full papers, including 4 poster presentations, presented together with 3 invited papers were carefully reviewed and selected from 50 submissions. The papers are organized in topical sections on robust watermarking, video watermarking, steganography and steganalysis, multimedia watermarking and security protocols, as well as image forensics and authentication.