A robust image watermarking scheme invariant to rotation, scaling and translation attacks

A robust digital image watermarking scheme that is resistant to both signal processing and geometric attacks is proposed. The watermark is embedded in the Discrete Cosine Transform domain in a spread-spectrum format and Vector Quantization techniques used to compress the image. The recovery of the watermark after rotation, scaling and translation attacks is done by using Harris corner detector-based feature-points to get a Delaunay tessellation which is used to reverse the attacks. In situations where RST attacks lead to formation of substantial dark areas on the image, some reference feature-points are lost and recovered watermark is poor or entirely lost. In our proposed scheme, a procedure of estimating the RST attacks is employed by taking an average of selected triangles in the tessellation. Computer simulation results using MATLAB have been used to confirm the accuracy of our proposed scheme.