RESULTS OF THE ASTM FIELD-TEST OF TRISTIMULUS WEIGHTING FUNCTIONS

In 1993, the American Society for Testing and Materials carried out a field test of newly calculated tristimulus weighting factors. These we ighting factors had been calculated by a method proposed by Venable. T he test also included a method of correction for bandpass dependence p ut forth by Stearns. The purpose of the trial was to assess the possib le reduction in bandpass dependence introduced by each of these sets o f weights. A large number of sets of spectral data were gathered from the cooperators in the field test. Results of integration by the vario us sets of tristimulus weighting factors were calculated A total of 15 120 color differences were calculated and statistics were derived to test the probable error resulting from each method of correction. Erro rs attributable to bandpass dependence were on the order of a few tent hs to as much as one CIELAB unit when uncorrected weight sets were use d. These errors could be reduced to a few hundreths of a CIELAB unit, and in some cases to a few thousandths of a unit, by employing one cor recting strategy or the other. An overall mix of strategies was ultima tely chosen to minimize the bandpass dependence over the entire range of weight sets. Utilizing this mixed strategy, the median error introd uced into 10-nm integration by bandpass dependence was only 0.004 CIEL AB units. (C) 1995 John Wiley & Sons, Inc.