The quantum realization of image linear gray enhancement

Abstract Linear gray enhancement is a spatial domain image enhancementtechnique commonly used in classical computers, mainly including image negative, image contrast stretching, and piecewise linear gray transformation. Inorder to realize these three linear gray enhancement techniques in the quantumcomputers, this paper proposes three types of linear gray transformationschemes for quantum images based on the generalized model of novel enhancedquantum image representation(GNEQR), and the quantum circuits that realizethese three transformation methods are constructed according to theschemes. The proposed circuits take advantage of efficient quantum arithmeticoperations and parallel Controlled-NOT modules to factor classical transformationsinto basic unitary operators such as the Controlled-NOT gates andthe Toffoli gates. The results show that the linear gray enhancement algorithmfor quantum images is better than the classical algorithm in both spatialcomplexity and time complexity.