Improved image watermarking using pixel averaging and unbiased retrieval

Digital watermarking based on pixels modification for color image is considered in this paper. Its operations are described and its performance is investigated. Based on our observations, a method based on pixel averaging and unbiased watermark retrieval is proposed in order to improve the efficiency of the considering watermarking method. Particularly, we first apply the pixel averaging technique to create the localized luminance component, and used it to fine tune the watermark signal strength. We then remove some biased watermarked pixels in the watermark retrieval process to increase accuracy of the recovered watermark. The experimental results show the watermark retrieval improvements in term of NC, compared to the previous watermarking methods. The robustness against different types of attack at various strengths is also evaluated and compared.