Reliable watermark detection method based on analysis of correlation
Jae Gark Choi · Optical Engineering · 2000
A digital watermark is a perceptually unobtrusive signal em- bedded in a multimedia asset, such as an image, for copyright protec- tion. In many cases watermark detection amounts to thresholding a cor- relation value between a watermark and a received image. Watermarking detection schemes can be classified into two types. Type 1 is based on a correlation process that is applied to the difference between an original image and an input image to be tested. Type 2 is based on a correlation process that is directly applied to an input image. Type 1 fails to prove the rightful ownership, while type 2 can do so. However, type 2 has a problem that type 1 does not have: The correla- tion between a watermark and an original image to be watermarked is too significant to be ignored, when it is normalized by the watermark's energy. In this paper, based on an analysis of the correlation, we pro- pose a novel watermarking scheme to minimize that effect. We verify the performance of the proposed scheme by experiments. © 2000 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(00)02612-X)