Robust image watermarking approach using polar harmonic transforms based geometric correction

Geometric distortions that cause displacement between embedding and detection are usually difficult for watermark to survive. It is a challenging work to design a robust image watermarking scheme against geometric distortions. In this paper, we propose a robust image watermarking approach using Polar Harmonic Transforms (PHTs) based geometric correction. The novelty of our approach is that (1) the optimal Nonsubsampled Shear let Transform (NSST), which can provide nearly optimal approximation for 2D image function, is used to embed digital watermark, and (2) the PHTs are exploited for estimating the geometric distortions parameters in order to permit watermark extraction. Experimental results show that the proposed approach not only provides better imperceptibility and robustness against various attacks (including common image processing operations and geometric distortions), but also yields better watermark detection performance than some state-of-the-art image watermarking schemes. (C) 2015 Elsevier B.V. All rights reserved.