A driver unit comprises a latch circuit for holding digital image data in a voltage state, a digital-to-analog converter, and a voltage compensator circuit for raising the analog display voltage. The digital-to-analog converter can access content of the digital image data from the voltage state in the latch circuit, and convert the digital image data into analog display signals. In other embodiments, a method of driving a liquid crystal display comprises storing digital image data in a latch circuit under a voltage state, accessing a content of the digital image data from the voltage state held in the latch circuit, selecting a reference voltage according to the content of the digital image data for converting the digital image data into analog display signals, and raising the analog display voltage for obtaining a driving voltage.