A DCT Domain Visible Watermarking Technique for Images

The growth of computer networks has boosted the growth of the information technology sector to a greater extent. There is a trend to move from conventional libraries to digital libraries. In the digital libraries images and texts are made available through the internet for scholarly research. At the same time care is taken to prevent the unauthorized use of the images commercially. In some cases the observer is encouraged to patronize the institution that owns the material. To satisfy both these needs simultaneously the owner needs to use visible watermarking. Visible watermarking is a type of digital watermarking used for protection of publicly available images. In this paper, we describe a visible watermarking scheme that is applied into the host image in the DCT domain. A mathematical model has been developed for that purpose. We have also proposed a modification of the algorithm to make the watermark more robust.