CIE 223 PDF

CIE 223 – Methods for Re-defining CIE D Illuminants

This Technical Report gives an overview of the construction of the tables describingCIE D illuminants, and proposes two methods to smooth the daylight illuminantspectral power distributions. The first method keeps the values originally determinedat the integer 10 nm intervals unchanged and interpolates between these fixed pointsto get smooth (twice differentiable) curves (minimal smoothing method). A secondalternative method smoothes more strongly, cutting fine structure maxima and minimaof the spectrum (highly smoothing method).

Examples show the consequences of both methods, pointing out that smoothing haslittle influence on colorimetric accuracy.

The Technical Committee recommends testing the provided tables based on the twosmoothing algorithms in practice and to urge users to test data of Table 4 which arebased on the highly smoothing method, and ask instrument constructors to test themethod for building D illuminant simulators with the eventual outcome of defining aCIE D50 and D65 standard source.

The publication provides a link to two Excel files: one for calculation of the SPD of adaylight illuminant for the different interpolation methods described in this report afterinput of a required CCT and another one providing the tables of the report .The publication is written in English, with a short summary in French and German.