Abstract
Utilizing a stockpile of efficient transformations consisting of channel of interest, channel swapping, and quantum Fourier transforms, a duple watermarking strategy on multi-channel quantum images is proposed. It embeds the watermark image both into the spatial domain and the frequency domain of the multi-channel quantum carrier image, while also providing a quantum measurement-based algorithm to generate an unknown key that is used to protect the color information, which accompanies another key that is mainly used to scramble the spatial content of the watermark image in order to further safeguard the copyright of the carrier image. Simulation-based experiments using a watermark logo and nine building images as watermark image and carrier images, respectively, offer a duple protection for the copyright of carrier images in terms of the visible quality of the watermarked images. The proposed stratagem advances available literature in the quantum watermarking research field and sets the stage for the applications aimed at quantum data protection.