Images are a convenient way for humans to obtain information and knowledge, but they are
often destroyed throughout the collection or distribution process. Therefore, image …

There have been numerous proposals in the literature to generalize the classical Fourier
transform by making use of the Hamiltonian quaternion algebra. The present paper reviews …

With the increasingly widespread use of medical images in medical institutions and
networks, the copyright protection of medical images has become increasingly urgent. Since …

The quaternion least mean square (QLMS) algorithm is introduced for adaptive filtering of
three-and four-dimensional processes, such as those observed in atmospheric modeling …

In this paper, by using the quaternion algebra, the conventional complex-type moments
(CTMs) for gray-scale images are generalized to color images as quaternion-type moments …

This paper presents two vector watermarking schemes that are based on the use of complex
and quaternion Fourier transforms and demonstrates, for the first time, how to embed …

This paper presents a new color image watermarking algorithm based on a fast structure-
preserving algorithm of quaternion singular value decomposition (QSVD). We first propose F …

Traditional sparse image models treat color image pixel as a scalar, which represents color
channels separately or concatenate color channels as a monochrome image. In this paper …

Moments and moment invariants have become a powerful tool in pattern recognition and
image analysis. Conventional methods to deal with color images are based on RGB …

Among the few existing color watermarking schemes, some use quaternion discrete Fourier
transform (QDFT). By modulating at least one component of QDFT coefficients, they spread …