Detection of image alterations using semifragile watermarks
Eugene T. Lin, Christine I. Podilchuk, Edward J. Delp · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2000
Digital watermarking research has generally focused upon two classes of watermarks, fragile and robust. Robust watermarks are designed to be detected even after attempts are made to remove them. Fragile watermarks are used for authentication purposes and are capable of detecting even minute changes of the watermarked content. Unfortunately, neither type of watermark is ideal when considering 'information preserving' transformations (such as compression) which preserve the meaning or expression of the content and 'information altering' transformations (such as feature replacement) which change the expression of the content. In this paper we describe a semi-fragile watermark for still images that can detect information altering transformations even after the watermarked content is subjected to information preserving alterations.