Synergistic compensation for RGB-based blind color image watermarking to withstand JPEG compression

Color image watermarking has achieved great success in applications such as copyright protection and content authentication. Nonetheless, color image watermarking individually implemented in RGB channels cannot survive JPEG compression attacks. This study introduces an auxiliary scheme that enables RGB-based watermarking methods to overcome this difficulty. The reason why a promising grayscale watermarking method suffers a severe setback from color image JPEG compression is first explained and the countermeasure used to remedy the deficiency is then delivered. The solution turns out to be the application of synergistic compensation (SC) to channels other than that used to embed the watermark. The benefit of the SC scheme is demonstrated through a well-developed blind watermarking method known as relative modulation implemented in the discrete cosine transform (DCT) domain. The experimental results confirmed that the incorporation of SC enabled RGB-based watermarking to triple the payload capacity and halve the bit error rates under JPEG compression with quality factors in the range of 40-90. Nonetheless, the gain in the capacity and the robustness against JPEG compression was accompanied by a minor drop of 1.174 dB in terms of peak signal-to-noise ratio.