Simulation of daylight for viewing and measuring color

Abstract

For convenience and reproducibility, daylight is artificially simulated for viewing and measuring colors. Daylight has been standardized in a way that is impractical. the evaluation of fluorescent materials requires simulation of the ultraviolet component of daylight or daylight through a window. Sources for viewing are assessed by spectroradiometry and standard computations. Sources for spectrophotometry may be tested the same way or by measuring radiance factors of fluorescent standards. Better manufacturing methods have improved glass filters. A new filter design method takes account of the spatiospectral nature of the source and affords many degrees of freedom.

Metrology, documentary standards, and color specifications for fluorescent materials

“…Once the reflected radiance factor is known, there are several methods for correcting the total radiance factor for small differences in the spectral power distributions of the desired standard daylight and its simulator. The basic equation for doing so was first derived by Eitle and (2) where S is spectral power, N is the relative number of quanta absorbed and converted to fluorescence, and the numerical subscripts represent the first (simulator) and second (standard) light sources. Values of N are calculated by integrating the product of the excitation spectrum X and S over the excitation wavelength region, A' .…”

New metamers for assessing the visible spectra of daylight simulators and a method of evaluating them

“…2,7,8 The assessment of D50 simulators was not included in CIE Publication 51. In March 1995, a committee of the International Organization for Standardization (ISO) requested me to derive sets of metamers for assessing D50 simulators.…”

“…The development and application of daylight simulators have been reviewed recently. 1,2 Correlated color temperature and chromaticity are often cited specifications of the quality of daylight simulators, but they are very weak specifications. For a given correlated color temperature, there is an infinite variety of possible chromaticities; and for every chromaticity, there is an infinite variety of possible spectral power distributions.…”