Reversible Authentication and Cross-Recovery of Images Using (t, n) Threshold and Modified-RCM Watermarking

This paper presents an image authentication scheme to verify the integrity of images. The method protects a group of n images mutually by applying a threshold mechanism to manipulate the recovery data. The authentication code and the recovery data are embedded using a modified reversible contrast mapping watermarking scheme. The proposed method not only can detect and locate the tampering activities on a watermarked image, but also can recover the tampered regions if at least t of the other n-1 watermarked images were intact. A fantastic characteristic of the proposed scheme is that the original images can be loss less restored if no watermarked image of the protected group was modified, making the technique suitable for protecting very sensitive images such as military or medical images. Experimental results show that the proposed scheme successfully detects various kinds of image alterations, and the corrupted images can be properly recovered using the proposed cross-recovery scheme.