A feature-based image watermarking scheme robust to local geometrical distortions

Geometric attacks are the Achilles heel for many image watermarking schemes. Geometric attacks can be decomposed into two classes: global affine transforms and local geometrical distortions. Most countermeasures proposed in the literature only address the problem of global affine transforms (e.g. rotation, scaling and translation). In this paper, we propose a blind image watermarking algorithm robust to local geometrical distortions such as row or column removal, cropping, local random bend, etc. The robust feature points are adaptively extracted from digital images and local image regions (circular regions) that are invariant to geometric attacks are obtained according to the multi-scale space representation and image normalization. At each local image region, the watermark is embedded by quantizing the magnitudes of the pseudo-Zernike moments. By binding digital watermark with local image regions, resilience against local geometrical distortions can be readily obtained. Experimental results show that the proposed image watermarking is not only invisible and robust against common image processing operations, such as sharpening, noise adding, JPEG compression, etc, but also robust against geometric attacks such as rotation, translation, scaling, row or column removal, copping, local random bend, etc.