This invention relates to an image processing method for improving the quality of an image to be displayed on a display device and to a liquid-crystal display device using the same, and aims at providing an image processing method for providing wide viewing angle and excellent tonal-intensity viewing angle characteristic and a liquid-crystal display device using the same. Combined together are a higher-luminance pixel to be driven higher in luminance than the luminance data of an image to be displayed and a lower-luminance pixel to be driven lower in luminance than the luminance data, to determine a luminance on the higher-luminance pixel and luminance on the lower-luminance pixel as well as an area ratio of the higher-luminance and lower-luminance pixels in a manner obtaining a luminance nearly equal to a desired luminance based on the luminance data.