A blind robust color image watermarking method using quaternion Fourier transform

A blind color image watermarking scheme based on quaternion discrete Fourier transform (QDFT) and uniform log-polar mapping (ULPM) is proposed. In this scheme, a binary meaningful watermark is first embedded into the real part of QDFT coefficient of middle frequencies. In order to make it robust to geometric attacks, a bipolar binary watermark is inserted by the following ULPM method. This second watermark can resist geometric attacks and is used so as to invert such a transformation. Once the geometric transform is reversed, the meaningful watermark can be then extracted. Furthermore, several blocking watermarking embedding approaches in QDFT domain are compared to obtain better robustness against common signal operations. Compared to other existing methods, experimental results show that the proposed method achieves better performance against common signal operations and geometric attacks.