Color image zero-watermarking based on fast quaternion generic polar complex exponential transform

As one promising solution, zero-watermarking techniques have been proposed to enhance the image visual quality and applied to protect the intellectual property rights of the medical images, remote sensing images and military images. Owing to their favorable image description capability and geometric invariance, moments and moment invariants have become a popular tool for the zero-watermarking. However, two issues of the moments-based zero-watermarking methods should be addressed: First, most of them ignore the analysis and experiment on discriminability, resulting in a high false positive ratio; Second, direct computation of the moments from their definition is inefficient, numerically unstable and inaccurate, which severely affects the performances of these moments-based methods. To overcome the two challenges, in this paper, we present a Fast Quatemion Generic Polar Complex Exponential Transform (FQGPCET) based color image zero watermarking algorithm. We first propose a novel computation strategy, i.e. FGPCET, to solve the moments computing problems. We then show that it is possible to generate a robust and discriminative image feature, by mixing the low-order QGPCET moments/coefficients. And finally, we develop a new color image zero-watermarking approach using FQGPCET and asymmetric tent map. Theoretical analysis and experimental results show that the proposed zero-watermarking algorithm achieves a good trade-off between robustness and discriminability, and has certain superiority in terms of security, capacity and time complexity.