A two-step watermarking attack using long-range correlation image restoration

This paper presents an efficient scheme for blind watermark attacking using the concept of matching of the long‐range data. The main idea of the proposed attack is to add plenty of noise to the watermarked image and then try to restore an unwatermarked copy of the noisy image. The aim is to destroy the watermark information without accessing the parameters used during the watermark embedding process. So, it allows our approach to be completely free from any pre‐assumption on the watermarking algorithm or any other parameters that is used during the watermark embedding procedure. Experimental results show the proposed algorithm’s superiority over several other traditional watermarking benchmarks such as Stirmark and Optimark. Peak signal‐to‐noise ratio of the watermarked image after applying the proposed attack is more than 45 dB, and the normalized cross‐correlation for the extracted watermark is lower than 0·4, so the watermark is not detectable after our attack. Copyright © 2011 John Wiley & Sons, Ltd.