Analysis of the role played by error correcting coding in robust watermarking

Robustness is one of the fundamental requirements of digital watermarking; for some applications. By modeling digital watermarking as digital communications, many authors proposed to use error correcting coding (ECC) to improve watermarking robustness. However, a fact has long been neglected. That is, due to the requirement of imperceptibility for watermarking, the redundancy introduced by ECC will lead to a decrease of the watermark strength. Hence, a question arises. Could ECC effectively improve the robustness of watermark? This paper investigates this problem from both theoretical analysis and experimental work perspectives. Our conclusion is that ECC cannot effectively improve the robustness of watermarking against most attacks, in particularly, conventional signal processing procedures and noise corruption. The only exception is attacks such as cropping, where ECC possibly improves the robustness of watermarking.