A Robust Quantum Watermark Algorithm Based on Quantum Log-polar Images

摘要

Copyright protection for quantum image is an important research branch of quantum information technology. In this paper, based on quantum log-polar image (QUALPI), a new quantum watermark algorithm is proposed to better protect copyright of quantum image. In order to realize quantum watermark embedding, the least significant qubit (LSQb) of quantum carrier image is replaced by quantum watermark image. The new algorithm has good practicability for designing quantum circuits of embedding and extracting watermark image respectively. Compared to previous quantum watermark algorithms, the new algorithm effectively utilizes two important properties of log-polar sampling, i.e., rotation and scale invariances. These invariances make quantum watermark image extracted have a good robustness when stego image was subjected to various geometric attacks, such as rotation, flip, scaling and translation. Experimental simulation based on MATLAB shows that the new algorithm has a good performance on robustness, transparency and capacity.