This book constitutes the thoroughly refereed post-proceedings of the 9th International Workshop on Information Hiding, IH 2007, held in Saint Malo, France, in June 2007.

The 25 revised full papers presented were carefully reviewed and selected from 105 submissions. The papers are organized in topical sections on new steganographic schemes, watermarking schemes, computer security, steganography and code theory, watermarking security, steganalysis, watermarking and re-synchronization, fingerprinting, forensics, and steganalysis.