An improved double image digital watermarking scheme using the position property

In the last few years, researchers have found that the security of multiple watermarking schemes are more than single watermarking schemes. In 2007, Hu et al. proposed a robust and simple scheme that used two watermark images. However, it had an ambiguity problem that the holder can claim ownership of the others copyright holder’s images. This paper solves the problem of Hu et al.’s scheme by using the position property of the original image. Although our results show that the robustness test of the proposed scheme presented a slightly lower quality than Hu et al.’s scheme, the ambiguity problem does not occur in our proposed scheme.