Stiles & Burch (1955) 2-deg individual colour matching functions


Individual 2-deg colour matching functions of Stiles & Burch (1955). Data are for primaries at 15500 (645.16), 19000 (526.32) and 22500 (444.44) cm-1 (nm) transformed from the instrument primaries of 15418 (648.59), 18997 (526.40) and 22456 (445.32) . Data are given for 10 subjects, each of whose sex and age are noted in the top row. The final columns gives the mean data. The values in red for Observer 2 are mean values for the group (see next).

Summary of and extracts from NPL Report QU68 by P.W. Trezona

The individual data, which were originally thought to be lost, were retrieved as computer print outs. The individual data, however, had not been corrected for "small changes in measurement of spectral responsivity of a photocell and spectral transmission characteristics of neutral filters during the course of the experiment". In addition, in obtaining the 1955 mean function, data at two wavelengths for observer No. 2 were omitted and replaced by population mean (values in red in the Excel table). After applying the corrections to the arithmetic mean of the individual data, followed by the necessary normalisation procedure, agreement was reached with the mean values published by Stiles and Burch.

However, there are still small discrepancies between the mean colour matching functions based on the individual data and the published means (e.g., Wyszecki & Stiles, 1982,  p. 334), which "arises because of the order in which the operations were carried out".

For more complete information, see NPL Report QU68, or its reprint as Trezona (1987).


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 (1955) with an appendix by W. S. Stiles & J. M. Burch. Optica Acta, 2, 168-181.

Stiles, W. S., & Burch, J. M. (1959). NPL colour-matching investigation: Final report. Optica Acta, 6, 1-26.

Stockman, A., & Sharpe, L. T. (2000). Spectral sensitivities of the middle- and long-wavelength sensitive cones derived from measurements in observers of known genotype. Vision Research, 40, 1711-1737.

Trezona, P. W. (1984). Individual Observer Data for the Stiles-Burch 2° Pilot Investigation. National Physical Laboratory Report QU68

Trezona, P. W. (1987). Individual observer data for the 1955 Stiles-Burch 2° pilot investigation. Journal of the Optical Society America A, 4, 769-782.

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