Among the implementations described herein is a gamma voltage generator which includes a first resistor string that is connected between a 0-th terminal and a first terminal and outputs first gamma voltages, a 0-th gamma amplifier that outputs a 0-th tap voltage to the 0-th terminal by using a 0-th reference voltage, a first variable tap gamma amplifier that outputs a first tap voltage to the first terminal by using a first reference voltage, and a gamma control logic circuit that selectively activates a first tap change signal based on a first grayscale ratio of first line data. The first variable tap gamma amplifier outputs a second tap voltage to a first central terminal of the first resistor string by using a second reference voltage, in response to the first tap change signal thus activated.