Rotation, scale, and translation resilient digital watermarking based on complex exponential function

In this paper, a novel digital image watermarking scheme has been proposed based on spread spectrum technique. By exploiting complex exponential function to generate a multiple-rings shaped pattern, the watermark is invariant to rotation and translation, and resilient to scaling without truly inverse transformations needed. The proposed technique is performed in regular frequency domain without additional log-polar mapping required which can reduce computational complexity of such transformation. Furthermore, the original image is not needed for detection in this technique. Experimental results demonstrate performance of the proposed scheme that the watermark is correctly detected although the image was undergone by geometric and non-geometric transforms.