a colorimeter method and apparatus is described that is used to accurately deduce the color of a source which is varying in intensity with respect to time . the colorimeter consists of a plurality of sensors with varied spectral responsivity , a means of shielding these sensors from the effects of ambient illumination and a computational element to analyze the temporal and intensity variation of the signal under measurement . the output from the sensors is integrated and analyzed based upon the measured light intensity , time variant , and characteristics of the source . sources such as crt monitors , flat panel displays , and stroboscopic illuminators , are typical representations of time variant sources .