Abstract & Overview
A scheme is proposed to watermark and recover unmarked greyscale images on quantum computers. The hitherto inaccessible data from a quantum image-watermark pair is extracted from their classical (conventional or non-quantum) versions using which two quantum sub-circuits are used to execute the two-tier transformations comprising of changes that: 1 embed a visible and translucent watermark logo in a predetermined sub-area of the quantum replica of the cover image 2 modify the remaining content of the cover image in a manner dictated by the watermark signal, so that the resulting distortions on the watermarked image are not easily discernible. Classical simulations of the image-watermark pairs and the various sub-circuits required to obtain the marked and unmarked images demonstrate the feasibility of the proposed scheme when the necessary quantum hardware are realised. The proposal advances available literature geared towards safeguarding quantum resources from unauthorised reproduction and confirmation of their proprietorship in cases of dispute thereby leading to commercial applications of quantum information.