A variably controlled LCD backlight is disclosed. The backlight includes a first light source that emits light within a first spectral power distribution and has a first radiant power output. A second light source emits light within a second spectral power distribution and has a second radiant power output. A detector detects the first and second radiant power outputs. A processor is connected to the detector and calculates chromaticity and luminance values of the emitted light based on the first and second radiant power outputs. The processor compares the calculated chromaticity and luminance values with desired chromaticity and luminance values, respectively. A controller is operationally connected to the processor and adjusts one or more of the first radiant power output and the second radiant power output in response to a difference between the calculated chromaticity and luminance values and the desired chromaticity and luminance values.