A gamma voltage generator includes a reference gamma selector, a reference gamma converter, and a gamma curve adjuster. The reference gamma selector selects a top reference gamma voltage and a bottom reference gamma voltage that are between first and second reference voltages. The reference gamma converter converts the bottom reference gamma voltage to a conversion reference gamma voltage based on the top reference gamma voltage. The gamma curve adjuster generates a plurality of grayscale gamma voltages based on the conversion reference gamma voltage and the top reference gamma voltage.