A method on digital watermarking image against geometric distortion

This paper describes a method against geometric distortion of digital watermarking image by means of Hausdorff distance measuring, which matches the feature points, and calculates similarity between two point sets (maximum distance). In this paper, Harris feature points are firstly extracted into feature point set according to the response of the Harris detector and the field size, and then secondly the Hausdorff distance is used to eliminate the image geometric deformation, thirdly, DWT(Discrete Wavelet Transform) transformation is conducted with the Harris feature points as centers, and also DCT(Discrete Cosine Transform) transformation is conducted in low-frequency LL domain; at last, watermark could be embedded and extracted in the DCT coefficient. The experimental results demonstrate that the embedded watermark image is well extracted and has high similarity after such geometric attacks as translation, rotation, scaling and shearing, so this method is a blind watermarking detection algorithm with strong robustness.