Improved image authentication using closed-form compensation and spread-spectrum watermarking

This paper presents an image authentication scheme based on compensated watermarking employing a Lagrangian-based closed-form solution to compensate for signature perturbation due to the embedding operation. The proposed scheme uses a spread-spectrum based watermarking technique and a blind detector, thus making it attractive for applications that may not have the original image available at the time of authentication. Existing compensated signature embedding frameworks use an iterative mechanism to reach a desired compensation. The iterative approach is time consuming and less effective than the closed-form approach proposed in this paper, which performs an accurate compensation in one step while meeting the minimum distortion criteria of image least mean square distortion to guarantee image fidelity. Simulation results are presented to show the proposed scheme´s efficiency and accuracy.