A luminance distribution at the highest gradation level is corrected to a curved plane luminance distribution in such a manner that the maximum gradation input to a display panel shows a curved luminance plane having the highest luminance at the center of the display panel and a lower luminance in the peripheral area of the display panel. The luminance distribution at the minimum gradation is corrected in such a manner that the minimum gradation shows a curved luminance plane having the lowest luminance at the center of the display panel and a higher luminance in the peripheral area of the display panel.