Image watermarking by embedding watermark into two chrominance channels

In this paper, we propose a method to improve the performance of the digital watermarking based on the modulation of image pixels in YCbCr color space. Basically, we divide the watermark into two parts, and embed each part into each chrominance channel; Cb and Cr. As a result, in the watermark extraction process, the number of the watermarked pixels used in the original pixel prediction process can be reduced by half. The experiments were carried out to verify our concept. The results show that the accuracy of the extracted watermark in term of NC is significantly improved compared to the previous methods. The improved robustness of the embedded watermark against different types of attacks at various strengths is also illustrated and compared.