Copyright Protection against Print-and-Scan Operations by Watermarking for Color Images Using Coding and Synchronization of Peak Locations in Frequency Domain

A watermarking method for copyright protection of color images against print-andscan operations is proposed. A watermark is embedded in an input image as coefficientvalue peaks that are circularly and symmetrically distributed in a middle band of the discrete Fourier transform (DFT) domain of the input image. By detecting the robust peaks in the DFT domain of a reproduced image obtained by scanning a printed version of a watermarked image, we can extract the embedded watermark to verify the copyright of the reproduced image. Experimental results are given to prove the feasibility of the proposed method.