Digital watermarking-based DCT and JPEG model

In recent years, digital watermarking techniques have been proposed to protect the copyright of multimedia data. Different watermarking schemes have been suggested for images. The goal of this paper is to develop a watermarking algorithm based on the discrete cosine transform (DCT) and image segmentation. The image is first segmented in different portions based on the Voronoi diagram and features extraction points. Then, a pseudorandom sequence of real numbers is embedded in the DCT domain of each image segment. Different experiments are conducted to show the performance of the scheme under different types of attacks. The results show that our proposed watermark scheme is robust to common signal distortions, including geometric manipulations. The robustness against Joint Photographic Experts Group (JPEG) compression is achieved for a compression ratio of up to 45, and robustness against average, median, and Wiener filters is shown for the 3/spl times/3 up to 9/spl times/9 pixel neighborhood. It is observed that robustness against scaling was achieved when the watermarked image size is scaled down to 0.4% of its original size.