Digital watermarking based on chaos game representation and discrete cosine transform

Digital watermarking is a means to protect multimedia copyright, and it will be subjected to various attacks. Therefore, the research on the robustness of watermarking algorithm is considered as a hot field. A digital image watermarking algorithm that can resist geometric attacks is proposed based on chaos game representation and normalization. Firstly, the original image is mapped to the geometrically invariant space using the image normalization. Then, according to the image characteristics and the human visual characteristics, the valid image is transformed by DCT transform and the embedding number is determined. At last, the embedding image and position are determined by chaos game representation and the embedding number, and the watermarking is embedded in the light of the embedding number and position into the embedding image. Analyzing experimental results, we can know that the algorithm is invisible, secure and robust against geometric attacks.