Page:Tristimulus specification of the Munsell book of color from spectrophotometric measurements (IA jresv31n1p55).pdf/24

 Graphs similar to figures 2 to 8 could of course be plotted for the other illuminants, using the data given in table 2. While this has not b een done for the present paper, it has seemed of interest to show the effect of the illuminant on the location and shape of the network. This is done in figure 9, where the values of x and y for Munsell value 5/ are plotted to the same scale for the four illuminants.

Differences between the methods used by Glenn and Killian and those used at the National Bureau of Standards are understood to be as follows: (1) The Glenn-Killian spectrophotometric data were obtained with samples backed by "a standard white substance," the National Bureau of Standards data with samples backed with black paper, (2) the calibration curves (see above) run on each sheet at the National Bureau of Standards were not used by Glenn and Killian, and (3) the Glenn-Killian colorimetric computations were made by the selected-ordinate method, the NBS data by the weighted-ordinate method.

Spectrophotometric differences caused by the backing are illustrated in figure 10, in which are shown the curves obtained on four Munsell samples, each sample being run first with white backing and