The Munsell Color Science Laboratory has developed a new method for determining color matching functions. It relies on a mathematical model that expresses color matching functions as the product of linear transforms of the cone action spectra and variable transmittances of the lens and macula for each observer. With this model, the full spectral tristimulus functions can be computed from a minimum of five visual matches. A visual colorimeter was designed to implement the MCSL model. The current instrument utilizes CRT primaries and seven interference filters to make matches to simulated daylight in a 2 bipartite field. The system was designed to minimize the strain on observers. Color matching functions of naive observers can be measured in approximately 30 minutes. Results from an individual observer correlated well with data collected on the National Research Council of Canada\u27s Trichromator. Color matching data for a single observer for 20 repetitions and 18 observers were measured. The variability for the single observer for 20 repetitions over a month\u27s time was found to be similar to the uncertainty of matching within a measurement session. The variability of the 18 observers was found to be much larger. The results were compared with the CIE standard deviate observer. The CIE standard deviate observer showed variability similar to that of the single observer but much larger than the variability of the 18 observers evaluated in this research
