### CIE
(1931) 2-deg color matching functions

### Data key

**Columns**

- Wavelength (nm)
- color matching function
- color matching function
- color matching
function

### Notes

The CIE 1931 2-deg CMFs (CIE, 1932), which form the basis for virtually all 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*(l)
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.

The Judd and Judd-Vos
modifications are attempts to overcome this problem.

See also Table I(3.3.1) of Wyszecki & Stiles (1982).

### References

CIE. (1926). *Commission Internationale de l'Eclairage Proceedings, 1924*.
Cambridge: Cambridge University Press.

CIE. (1932). *Commission Internationale de l'Eclairage Proceedings, 1931*.
Cambridge: Cambridge University Press.

Guild, J. (1931). The colorimetric properties of the spectrum. *Philosophical
Transactions of the Royal Society of London, A230*, 149-187.

Stiles, W. S. & Burch, J. M. (1955). Interim report to the Commission
Internationale de l'Eclairage 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.

Wyszecki, G., & Stiles, W. S. (1982). *Color Science: concepts and methods,
quantitative data and formulae*. (2nd ed.). New York: Wiley.

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