D50 {colorSpec}

Standard Illuminant D50 (1964)

Description

D50.5nm

standard Illuminant D50, from 300 to 830 nm at 5 nm intervals.

Format

A colorSpec object organized as a vector, with 107 data points and specnames equal to 'D50'.

Details

This spectrum is not copied from a table from a CIE publication, though it does match such a table. It is computed using the function daylightSpectra() by following the special CIE recipe given in the References. The temperature is set to (14388/14380) * 5000 = 5002.781 Kelvin. The coefficients of the daylight components S_0, S_1, and S_2 are rounded to 3 decimal places. This linear combination is computed at 10nm intervals and then linearly interpolated to 5nm intervals. The result is normalized to value 1 at 560nm (instead of the usual 100), and finally rounded to 5 decimal places. See Examples.

References

Günther Wyszecki and W.S. Stiles. Color Science : Concepts and Methods, Quantitative Data and Formulae. Second Edition. Wiley-Interscience. 1982. Table I(3.3.4) pp. 754-758

CIE 15: Technical Report: Colorimetry, 3rd edition. CIE 15:2004. Table T.1, pp 30-32, and Note 5 on page 69.

Schanda, Janos. CIE Colorimetry, in Colorimetry: Understanding the CIE System. Wiley Interscience. 2007. p. 42.

See Also

ABC , D65 , daylightSpectra

Examples

#   the CIE recipe for computing D50.5nm
correction  = 14388 / 14380     # note 5, page 69 in CIE 15:2004
D50.10nm    = daylightSpectra( correction*5000, wavelength=seq(300,830,by=10), roundMs=TRUE )
D50.5nm     = resample( D50.10nm, seq(300,830,by=5), method='linear' )
D50.5nm     = round( D50.5nm, 5 )

summary( D50.5nm )
white.point = product( D50.5nm, xyz1931.1nm, wave='auto' )