A display driver for outputting gradation voltages corresponding to gradation data from an external device to pixels. The display driver includes a generator for generating a plurality of gradation voltages having a plurality of levels based on a reference voltage, and a selector for selecting at least one gradation voltage corresponding to the gradation data from the plurality of gradation voltages generated by the generator. The gradation data includes multi-bits for each color of red, green and blue, and the generator outputs or stops outputting each gradation voltage according to data for color reduction from the external device. The generator stops outputting at least one gradation voltage that is unnecessary for displaying as a result of the color reduction, when the color of the gradation data is reduced according to the data for color reduction.