Tampering with a watermarking-based image authentication scheme

We analyse a recent image authentication scheme designed by Chang et al. A watermarking-based image ownership and tampering authentication scheme, Pattern Recognition Lett. 27 (5) (2006) 439-446] whose first step is based on a watermarking scheme of Maniccam and Bourbakis Lossless compression and information hiding in images, Pattern Recognition 37 (3) (2004) 475-486]. We show how the Chang et al. scheme still allows pixels to be tampered, and furthermore discuss why its ownership cannot be uniquely binding. Our results indicate that the scheme does not achieve its designed objectives of tamper detection and image ownership.