A driver integrated circuit (IC) for a liquid crystal display (LCD) has a double column structure. The driver IC includes a first shift register unit, a first data latch unit, first and second decoders, and first and second output buffers. The first data latch unit receives and stores first and second group channel data in response to a clock signal generated by the first shift register unit. The first decoder receives the first group channel data and outputs gamma voltages corresponding to the first group channel data. The second decoder receives the second group channel data and outputs gamma voltages corresponding to the second group channel data. The first and second output buffers are aligned along a long edge of the driver IC and buffer the corresponding gamma voltages to drive corresponding channels. The first shift register unit and the first data latch unit are shared by upper and lower blocks to process the first and second group channel data together.