In one example embodiment, a method of operating an image data processing circuit which controls an operation of an organic light-emitting diode (OLED) display includes transforming at least one first RGB value into at least one luminance value and at least one chroma value. The method further includes adjusting the at least one luminance value and the at least one chroma value based on at least one first control value. The method further includes generating at least one second RGB value based on the at least one adjusted luminance value and the at least one adjusted chroma value. The method further includes outputting the second RGB values to the OLED display.