Zero-watermarking algorithm based on DC component in DCT domain

In recent years, with the rapid development of digital media technology, the number of Internet users has been increasing explosively while pictures play important roles in a network information carrier, which provides a good application background for the hidden communication. However, nearly all websites will conduct a transcoding process on uploaded pictures, which can cause unpredictable effects to carrier image's code rate, GOP (Group of Pictures) structure, QP (Quantization Parameters) and other key compression parameters. Obviously, it greatly limits most of the present information steganography based on compressed domain embedded applications. To solve this problem, this paper proposes an adaptive robust watermark method for watermark coding spread spectrum, combining the DCT transform domain and DC zero component. This method is based on image watermark encoding and achieves the purpose of embedding messages by selecting a certain number of DC values and expressing their mutual relations. Theoretically, watermarks embedded in DC components based on DCT transform domain have such advantages as strong robustness and good concealment, which are more conducive to resist compression or geometric attack. The experimental results show that this method improves the watermark information recovery rate of images with watermark carrier after different degrees of watermark attack as well as maintains good quality and robustness.