Quaternion Based Holistic Color Images Watermarking Algorithm

This paper presents a blind color image watermarking scheme using the combination of the holistic transformation of Quaternion Fourier Transformation (QFT) and Quaternion Singular Value Decomposition (QSVD). The host image is first divided into blocks followed by taking the QFT of each block. Then design watermarks that use the diagonal elements of the two unitary matrices obtained from the followed QSVD of each block and add the watermarks into the singular values of each block. The specially designed watermarks strongly improve the false positive rate of randomly selected images. The real singular values got from QSVD contain both luminance and chrominance information of the color image that ensure the watermarks to spread into all color components in the spatial domain. Experimental results demonstrate that the proposed watermarking scheme performs better than traditional multi-channel watermarking scheme and the existing quaternion-based watermarking scheme in imperceptibility and false positive rate of randomly selected images respectively.