Page:Tristimulus specification of the Munsell book of color from spectrophotometric measurements (IA jresv31n1p55).pdf/3

 color designation as well as those arising from the unknown history and usage of the Glenn-Killian samples prior to their measurement. Furthermore, the present authors desired to use in the spectrophotometric measurements certain methods of calibration regularly used at the National Bureau of Standards for such work. The measurements and computations described below were accordingly undertaken, and the diagrams and tables included in the present paper provide a means by which a color may be named without reference to a color chart, or by which the boundaries of the color-name blocks may be specified in terms of a fundamental color system. It is now possible to select the appropriate color name for a color when the fundamental specifications for that color are given.

Since the application of this system of color names will be made in the plant or in the field where the illumination used will usually be daylight, all of the techniques and computations, both for the color names and for the Munsell system, have primarily been made on the basis of ICI illuminant C. However, colorimetric data on the Munsell standards for other illuminants are also of interest. Accordingly, based on the same spectrophotometric data, tristimulus values have been computed for four illuminants-ICI illuminant C [9] (representative of average daylight), ICI illuminant A [9] (2,842°K [10], representative of incandescent illuminants), illuminant "D" [11, 12] (representative of lightly overcast north sky), and illuminant "8" [13, 14] (representative of extremely blue sky).

{[center|'''II. SAMPLES MEASURED'''}}

Prior to his death, Walter T. Spry, then manager of the Munsell Color Co., deposited one or more samples of all of the original paintings of the standards in the Munsell Book of Color with the Colorimetry Section of the Bureau. He also deposited repaints of all colors the original paintings of which had become depleted, together with new colors prepared up to 1935. In selecting the samples of each color to be measured, that painting was chosen which matched the color chip of the same designation in the Munsell Book of Color. In most instances the color differences between the originals and their repaints were negligible, but in several cases it was important to specify which painting was used. Therefore, for the purpose of accuracy and as a matter of record, the painting number of each sample measured is given.

The 2-value 2-chroma samples for the intermediate hues (10R,10YR, 10Y, etc.) were painted independently of the other 2-value 2-chroma samples, and the colors and the data are not as congruent with the other samples as they are with each other. These samples, as well as several 8-value 2-chroma samples for the intermediate hues, are not included in the Munsell Book of Color, but they were measured and the data are included in the present paper for the sake of completeness. One new sample, 10YR 8/8, recently received, is included. The complete list of samples measured is given in table 2.

The samples in the Munsell Book of Color were inspected under a strong source of ultraviolet radiant energy and also under a strong yellowish green light for fluorescence that might vitiate the spectrophotometric measurements [15]. No fluorescence was observed under either illuminant.