A multi-purpose digital image watermarking using fractal block coding

In this paper, a new multi-purpose watermarking technique is presented which satisfies both verification and authentication purposes simultaneously by embedding a binary watermark into the image. The proposed method uses a special type of fractal block coding with a local search region with contrast scaling and mean of range block as its parameters. It also utilizes Fuzzy C-Mean clustering to specify the watermark bits. To overcome the high computational complexity of fractal coding, a new simple coding method is also presented which improves the robustness of the watermarking and decreases the run time of fractal block coding in the watermarking procedure. To measure the fragility and robustness of the method to signal distortions such as JPEG compression, median filter, and additive noise, some experiments were employed. The experimental results showed that the proposed method has provided a sensitive authentication and a reliable verification.