<p>CIE (1931) 2-deg colour matching functions</p><p>Data key</p><p>Columns</p><p>1. Wavelength (nm) 2. x(l ) 3. y(l ) 4. z (l ) </p><p>Notes</p><p>The CIE 1931 2-deg CMFs (CIE, 1932), which form the basis for most practical colorimetry, are based on the chromaticity coordinates obtained by Guild (1931) and by Wright (1928). Chromaticity coordinates, however, provide only a relative measure of the ratios of the three primaries needed to match each spectrum color, whereas CMFs specify absolute energy values. In order to reconstruct the CMFs from the Wright and Guild data, it was assumed that the CIE1924 V ( l ) photopic luminosity function (CIE, 1926) is a linear combination of the three CMFs (see Wyszecki & Stiles, 1982), for a description of the reconstruction and for the tabulated values. It has long been clear that the CIE1924 V() that was used to construct the CIE 1931 2- deg CMFs seriously underestimates sensitivity at wavelengths below 460 nm, so that these CMFs are seriously in error at short wavelengths. </p><p>The Judd and Judd-Vos modifications are attempts to overcome this problem. </p><p>See also Table I(3.3.1) of Wyszecki & Stiles (1982). </p><p>References</p><p>CIE. (1926). Commission Internationale de l’Éclairage Proceedings, 1924. Cambridge: Cambridge University Press.</p><p>CIE. (1932). Commission Internationale de l’Éclairage Proceedings, 1931. Cambridge: Cambridge University Press.</p><p>Guild, J. (1931). The colorimetric properties of the spectrum. Philosophical Transactions of the Royal Society of London, A230, 149-187.</p><p>Stiles, W. S. & Burch, J. M. (1955). Interim report to the Commission Internationale de l’Éclairage Zurich, 1955, on the National Physical Laboratory's investigation of colour-matching. Optica Acta, 2, 168-181. Wright, W. D. (1928). A re-determination of the trichromatic coefficients of the spectral colours. Transactions of the Optical Society, 30, 141-164.</p><p>Wyszecki, G., & Stiles, W. S. (1982). Color Science: concepts and methods, quantitative data and formulae. (2nd ed.). New York: Wiley.</p>