In an image processing system for a liquid crystal display a frame converter receives an original frame signal and produces a double frequency frame signal. A high pass filter performs a high pass filtering on the double frequency frame signal and produces a high pass double frequency frame signal. A delay device performs a delay operation on the double frequency frame signal and produces a delayed double frequency frame signal. A local contrast measurement device measures a contrast of the double frame signal and produces a local contrast signal. A high frequency gain device performs a gain adjustment on the high pass double frequency frame signal based on the local contrast signal and produces a gained high pass double frequency frame signal. A mixer is employed to mix the gained high pass double frequency frame signal and the delayed double frequency frame signal and produce an output frame signal.