A gamma-voltage generation circuit is arranged to output groups of gamma voltages. The circuit has a resister string and several switches. The resistor string has several resistors connected in series and is grouped into several segments, wherein each of the segments provides one of the gamma voltages. The switches respectively couple to several nodes between the resistors in one of the segments. Wherein the switches are closed when one of the groups of the gamma voltages are output and the switches are opened when another one of the groups of the gamma voltages are output.