A Blind DCT Domain Digital Watermarking

A new blind gray-level watermarking scheme is described. In the proposed method, the host image is first divided into 4◊4 non-overlapping blocks. For each block, five first AC coefficients of its DCT are then estimated using DC coefficients of its neighbor blocks. A gray-level watermark is then added into estimated values. Since embedding watermark does not change the DC coefficients, watermark extracting could be done by estimating AC coefficients and comparing them with their actual values. Several experiments are made and results suggest the robustness of the proposed algorithm.