In a display system having pixels made up of electroluminescent devices (ELDs) of three or more basis colors, a control circuit receives for each pixel a specification of a desired color to be displayed on the pixel, and determines a required driving voltage or electrical current for ELDs of each basis color, the required driving voltage or electrical current being determined from values of driving voltages or electrical currents associated with predetermined colors within the spectral locus or the purple line of human vision.