Device and method for reducing power consumption in display devices

Devices and methods are disclosed that reduce the amount of power consumed by an existing display device irrespective of the display mode. One such method includes recognizing a display mode related to light and dark when no voltage is applied to the display device. The method also includes determining a shift direction for the values of an image based on the recognized display mode so that power consumption is reduced in the display device. The method further includes determining a shift amount for the values of the image in accordance with a predetermined process, and converting the values of the image to be converted in the determined shift direction in accordance with the determined shift amount.