Robustness of watermarking: Is error correcting coding effective

Robustness is one of the most important requirements of digital watermarking for many applications. Spread-spectrum based methods are not effective enough to ensure their robustness. By modeling digital watermarking as digital communications, several researchers proposed using error correcting coding (ECC) to improve robustness. However, an important fact that has long been neglected is that due to the imperceptibility requirement, the redundancy introduced by ECC will lead to a decrease of the magnitude of watermark signal. Therefore, a problem arises naturally: Could the usage of ECC effectively improve the robustness of watermarking? This paper addresses this problem from the perspectives of both theoretical analysis and experimental investigation. Our investigation shows that ECC cannot effectively improve the robustness of watermarking against a great majority of various attacks except for cropping and jitter attacks. Hence, ECC should not be considered as a universal measure that can be employed to enhance robustness of watermarking.