Zero Digital Image Watermarking Method Against Rotation Attack Based On Block DCT Transform

The existing digital image watermarking method based on DWT without resisting to geometric attack ability,for example,the image is rotated by little angles and the author could not detect watermark. In order to improve the zero digital image watermarking method against rotation attack ability,the paper proposes one method based on DWT,which can against rotation attack ability efficiently. For rotation causing distortion,we make use of LPM (log-polar maping),which can transform rotation problem in Castesian coordinate to translation property in LPM coordinate. after translation,we use an exhaustive search to detect test image involves watermarking or not. The experiment results demonstrate the proposed method can obtain better visual effect,meanwhile,it is robust enough to some image degradation process such as adding noise,cropping,filtering and JPEG compression.