A Robust Digital Image Watermarking Algorithm Based on DCT Domain for Copyright Protection

Abstract

With the rapid development of various digital multimedia technologies, the works, such as copying, downloading and publishing digital multimedia works via the Internet, are made very convenient. However, it also brings on a huge challenge to the copyright protection of digital multimedia works. How to effectively protect and authenticate digital multimedia works on the Internet has been a problem to be solved urgently. In this paper, a robust digital image watermarking algorithm, which embeds a meaningful binary image as the watermark, is proposed. Firstly, the watermarking algorithm scrambles the binary image used as the watermark by the toral automorphism system. Then, the discrete cosine transform on the blocks of a gay scale image used as the carrier image are carried out and the quantization table depicted in the JPEG standards, which are used when an image needs a relatively high compression rate, is used to quantize the DCT coefficients. After the quantization, some statistical characteristics of the coefficients which are still not equal to zero will be used to implement the embedding of the watermark. Given the embedding course of watermark mentioned above, this watermarking algorithm is expected to have great robustness, especially to JPEG compressing. The simulation experiment results also prove the effectiveness of the algorithm proposed.