Cocktail watermarking on images

摘要

A novel image protection scheme named "cocktail watermarking" improves over current spread-spectrum watermarking approaches. Two watermarks, which play complementary roles, are simultaneously embedded into an original image [I(x,y)] (100). The original image (100) is processed by an encoder (110) to mark the image with a so-called watermark to produce a watermarked image [I^(m)(x,y)] (130). The watermarked image (130) is distributed, e.g. over the Internet, and may be inadvertently or intentionally modified as represented by attack (150) to produce modified watermarked image [I*(x,y)] (170). A detector (180) processes attacked watermarked image (170), along with other information produced during the encoding phase, such as random watermark sequence [N] (120) and a mapping [m(x,y)] (122) which identifies where in watermarked image (130) watermark sequence (120) is hidden. This other information is not distributed along with the watermarked image, enabling a determination to be made whether the input to detector (180) is indeed a modified version of watermarked image (130).;The new watermarking scheme has the characteristic that, no matter what an attack is, at least one watermark typically survives well and can be detected. Results of extensive experiments indicate that our cocktail watermarking scheme is effective in resisting various attacks.