1. A liquid crystal display device, comprising: a liquid crystal panel including a pixel having red, green, blue and white sub-pixels; a mode selector that selects one from an RGB mode and an RGBW mode as a driving mode; an RGBW mode signal generating part that performs a color correction on RGB input data corresponding to the pixel and converting the RGB input data into RGBW data in the RGBW mode; and an output controlling part that outputs RGBW output data by performing a gamma conversion on the RGBW data in the RGBW mode and outputs the RGB input data and a W data for turning off the W sub-pixel as the RGBW output data in the RGB mode.