An organic light-emitting display device including a display panel, a power supply, a selective driver and a gamma change driver is disclosed. The display panel includes sub-pixels. The power supply is configured to output a drive voltage for driving the sub-pixels. The selective driver is configured to generate a control signal to enable selective drive between first and second driving schemes for a drive transistor in each sub-pixel, wherein the first and second schemes employ saturation and linear regions of the drive voltage curve respectively. The gamma change driver is configured to change a gamma based on the driving scheme selected by the selective driver.