A timing controller includes: a compensator to receive an image signal and to output a compensation image signal; a dimming range adjustor to receive a backlight dimming signal and to output a dimming range signal to adjust an active section of the backlight dimming signal; a smoothing processor to output a smoothing image signal to smooth the compensation image signal in response to the dimming range signal; and a data output part to output an image data signal by adding the smoothing image signal to the image signal.