A series of tests have been performed to evaluate the relative precision of the spectrophotometer and the differential filter colorimeter for color difference measurements at low reflectance levels. The conditions and techniques of measurement are described and the results are tabulated and discussed. The superior precision of the colorimetric measurements at reflectance levels of 6 percent and below is demonstrated.
A. R. MACDONALD and G. P. BENTLEY, "Color Difference Comparisons in Low Reflectance Regions (A Study of the Precision of Spectrophotometric and Colorimetric Comparisons)," J. Opt. Soc. Am. 45, 366-370 (1955)