Geometrically invariant watermarking using affine covariant regions

In this paper, we present a robust approach to digital watermarking embedding and retrieval for digital images. The affine-invariant point detector is used to extract feature regions of the given host image. Image normalization and dominant gradient orientation alignment are applied to these feature regions to achieve scaling and rotation invariance. Thereafter, watermarks are embedded in these feature regions. The advantage of this proposed approach is demonstrated by a large amount of experiments, which can against different attacks, such as common image processing, rotation, scaling, cropping, and several other affine transformations.