A Robust Contourlet Based Image Hash Algorithm

Image searching and authentication have become strong requirements in the digital world. Image perceptual hashing has been proposed to meet them. In this paper, a rotation resilient image hashing algorithm is presented. In the algorithm, the position information of original image is extracted to adjust the rotation. Then the features of the image are extracted by contourlet transform. The key-dependence was introduced in this step by random blocking. The rotation is compensated by position information. Thus our algorithm is very robust to rotation attack. Benefited from the efficient image representation capability of contourlet transform, the robustness and discrimination of proposed method are improved. The experimental results show that the proposed method is better than some existing key dependent methods in robustness.