A method of operating a lighting fixture comprising a plurality of discrete illumination sources of distinguishably different color coordinates comprises determining target color coordinates and luminous flux at which to operate the lighting fixture, determining input electrical power values for each of the plurality of discrete illumination sources that substantially produce the target color coordinates and luminous flux by referencing a calibration data lookup table having calibration data based on measurements of the plurality of discrete illumination sources, determining a color mixing zone defined by three distinguishably different color coordinates of the plurality of discrete illumination sources within which the target color coordinates lie according to the calibration data, determining luminous flux ratios for each of the plurality of discrete illumination sources having one of the three distinguishably different color coordinates defining the color mixing zone that substantially produces the target color coordinates.
