A Comparative Evaluation of Semi-Fragile Watermarking Algorithms

Semi-fragile watermarking techniques aim to prevent tampering and fraudulent use of modified images. A semi-fragile watermark monitors the integrity of the content of the image but not its numerical representation. Therefore the watermark is designed so that the integrity is proven if the content of the image has not been tampered with, despite some mild processing on the image. However if parts of the image are replaced with the wrong key or are heavily processed, the watermark information should indicate evidence of forgery. In this paper we compare the performance of eight semi-fragile watermarking algorithms in terms of their miss probability under forgery attack, and in terms of false alarm probability under non-malicious signal processing operations that preserve the content and quality of the image. We propose desiderata for semi-fragile watermarking algorithms and indicate the promising algorithms among existing ones.