Robust Image Watermarking Algorithm against Shearing

In this paper, a robust digital watermarking method against shearing based on orthogonal function system is introduced. The proposed method makes use of the complete generalized orthogonal properties of Haar orthogonal function system to achieve the piece-based orthogonal transform on the image. The significant middle frequently coefficients in the transformation matrix are picked up, based on characteristics of the image visual system and the Haar orthogonal transform. The watermark is adoptively weighed to the middle frequently matrix. The method improves the validity of watermarking and shows excellent advantage against shearing attack. Experimental results show that the Haar orthogonal function system based watermark approach can provide an excellent protection under geometric attacks.