We introduce an optical approach, which can improve the gamma-curve distortion using a pair of positive and negative A-type retardation films only for various liquid crystal display (LCD) modes. Optimization of a pair of A-plates was performed by calculating the polarization difference (Delta p) between the normal and oblique incidence under a voltage applied state as functions of the retardation and the optical axis of the used A-plates. From the calculated results, LCD modes show an improvement of the gamma-curve distortion over the 60% without any loss of optical performance in the dark state.