Image watermarking system based on centroid projection

We propose an image watermarking system aiming at reducing false positive rate based on the location changes of centroids of several selected points. Two secret keys are used to determine the number of selected points and the random number seed in the LL band of DWT domain, respectively, of the original and watermarked images. The number of modified pixel values is basically a tradeoff between the transparency of the image quality and the robustness against attacks. The two secret keys and the calculated centroid should be sent as the side information along with the watermarked image from the embedding end to the extracting end. The experimental results show that the proposed system yields not only high robustness against filtering and compression attacks but also low false alarm rates after attacking.