Digital watermarking method using compression concept and coefficient difference

In this paper, a robust watermarking technique for embedding a watermark into grey-level image is proposed. It is well known that lossy compression will remove high-frequency components of an image. Using the concept of compression to embed a watermark into the coefficient difference between the middle frequency of the original and the compressed images, the proposed scheme provides a robust characteristic and maintains good visual quality of an image. The watermark is designed to be extracted without the original image so that the application is more feasible in practice. Furthermore, security is strongly enhanced by the chaos technique which is used in the proposed scheme. Experimental results show that the scheme features not only imperceptibility and security, but also robustness against various image processing attacks such as JPEG and JPEG2000 lossy compression techniques, filtering, noise adding, scaling, cropping, etc.