A liquid crystal display is disclosed. The liquid crystal display includes a liquid crystal display panel; a backlight unit; a panel drive circuit; a timing controller; a data stretching unit that modulates an internal video signal using a data stretching curve determined depending on a brightness of the internal video signal for a self-screen drive; an internal memory; a self-screen drive controller; a scaler unit; a selection unit; an internal power circuit; an external power circuit; and a microprocessor that blocks an output of the external power circuit from being supplied to the scaler unit in the self-screen drive.