Blind watermarking based on coset and scale quantization in DWT domain

In the recent years, with the rapid development of the network multimedia systems, digital watermarking technique has become a feasible solution to copyright protection. In this paper, we propose a watermarking system for still images on basis of scale quantization and coset. The method utilizes a suitable scale factor to scale host image, then according scale version of host image to construct coset for embedding watermark information. Our scheme makes a tradeoff between imperceptibility and robustness, and achieves a higher capability against steganalysis than most of the current quantizing directly coefficients embedding methods. The extraction algorithm retrieves the hidden information bits without host images. Experimental results indicate the robustness of the method to general signal processing attacks.