1. A method of controlling an OLED display to achieve desired color points and brightness levels in an array of pixels in which each pixel includes at least three sub-pixels having different colors and at least one white sub-pixel, said method comprising selecting a plurality of reference points in the pixel content domain with known color points and brightness levels, for each set of three sub-pixels of different colors, determining the share of each sub-pixel to produce the color point and brightness level of each selected reference point, and selecting the maximum share determined for each sub-pixel as the peak brightness needed from that sub-pixel.