Geometric invariant semi-fragile image watermarking using real symmetric matrix

In order to improve the detection of malicious tampering of images, it is necessary to decrease the fragility of hidden watermarks, even for digital images which have been distorted incidentally. However, watermarks are sensitive to geometric distortions. In this paper, we propose a new invariant semi-fragile digital watermarking technique based on eigenvalues and eigenvectors of a real symmetric matrix generated by the four pixel-pair. And the multi-rings Zemike transform (MRZT) is proposed to achieve geometric invariance. A signature bit for detecting malicious tampering of an image is generated using the dominant eigenvector. The MRZT method is against the geometric distortions even when the image is under malicious attacks. The experimental results show that this algorithm can resist high quality JPEG compression, and improve the detection performance of various malicious tampering.