Page:Journal of the Optical Society of America, volume 30, number 12.pdf/21

DECEMBER, 1940

HREE reports have been made by the National Bureau of Standards on papers representative of the Munsell color system: First, a very early report (No. 10,696) dated February 28, 1912, from P. G. Nutting to A. H. Munsell, giving dominant wave-length, percent white, and the reflection coefficient on six cards, which included the principal hues at 5/5, submitted to the Bureau by Mr. Munsell (1) ; second, report No. 23,998 dated June, 1919, to the Munsell Color Company (later published as Bureau of Standards Technologic Paper No. 167 by Priest, Gibson, and McNicholas) (2) giving spectro-photometric data on nine neutral grays and three samples of each of the five principal hues; and third, report No. 46,045 (1), dated September 14, 1926, on “The spectral reflection of 70 representative colored cards from the Munsell color system.” This third report was made to the Munsell Research Laboratory as a part of the cooperative work then being carried on between the two laboratories under the supervision of I. G. Priest, at that time chief of the Colorimetry Section, National Bureau of Standards, and A. E. O. Munsell, Director of the Munsell Research Laboratory.

The first report is not based on spectrophotoetric data, and was made before publication of the complete Atlas of the Munsell Color System (3), but it is noted here because it indicates that from a very early date A. H. Munsell was intent upon standardization, particularly of the five basic “middle colors” around which his system was built. The second report has been published (2) and is therefore a matter of record. The data of the third report, obtained in 1926, are published for the first time in this paper.

For this 1926 test 70 samples were selected by A. E. O. Munsell for measurement, and submitted, not only as an exemplification of the Munsell system as it existed in 1926 but as an exemplification, as far as it was then possible, of the original system developed by A. H. Munsell. The samples were either the original paintings which had been kept unexposed in the files, or, where such were not available, duplicates that had been made to match the originals as accurately as possible whenever the supply of an original color was nearly exhausted. The samples were submitted in sheets 8 by 8 inches square, and were representative of the most highly saturated colors of the system as it then existed. Their Munsell notations are given in.

Notations of the 70 Munsell Atlas samples measured at the National Bureau of Standards in 1926, NBS test 46,045.

Three instruments were used to obtain the spectrophotometric data given in the 1926 report, all of the values being expressed relative to freshly prepared magnesium oxide.

Diffuse illumination, normal reflection, visual method

The König-Martens spectrophotometer with auxiliary equipment (4) was used to obtain data under these conditions. Measurements were made at every 20 m&mu; from 420 to 720 m&mu;. In