Multipurpose digital watermarking for copyright notification and protection

This paper proposes a novel multiple watermarking scheme for different purposes: to notify the copyright owner with a reversible visible watermark in the region of interest (ROI) of the original image, and to protect the copyright with an invisible watermark in the remaining part of the image. It can fully remove the visible watermark from the dual watermarked image and restore the ROI. The invisible watermark is embedded into the low DCT frequency coefficients, and the visible watermark is embedded using a bijective mapping function, which is based on two secret keys. The experimental results illustrate that only users with correct key can restore the ROI and that the invisible watermark is robust against common image processing attacks.