Automatic image authentication and recovery using multiple watermarks

We propose a novel scheme of Automatic image authentication and recovery, in which the altered region of the image can be detected and recovered in a fully automated fashion. We use a fragile digital watermarking technique based on eigenvalues and eigenvectors of a real symmetric matrix generated by the four pixel-pair. The signature bits for detecting malicious tampering of an image are generated using the dominant eigenvector. To achieve high-quality image recovery, we finally insert the binary halftone image converted from the original image into the watermarked image to obtain the protected watermarked image. By watermark extraction, we can determine whether the watermarked image has been tampered or not. If the watermarked image has been tampered, we can automatically localize the altered region, and achieve image recovery. Finally, experimental results are given to show the effectiveness of the proposed scheme.