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Journal of Research of the National Bureau of StandardsVol. 6 1, No.5, November 1958Research Paper 2911Central Notations for the Revised ISCC-NBSColor-Name BlocksKenneth 1. KellyNickerso n and Newhall published, in 1941, the central notations of the original ISCC NBS (Inter-Society Color Council-National Bureau of Standards) color-name blocks whichwere u sed in the preparat ion of the soil and rock color-name charts. In 1955, the ISCCNBS color-nam e blocks were r evised to accord more closely with usage in the texti le andother fi eld s (N BS Circu lar 553). The central notations of these revised color-name blockshav e been compu te d and are given in the prese nt paper in tabu lar form. A color charts llow.ing t he central colors of the 267 ISCC--NBS color-n ame blocks wou1d se rv e for rapiddetermination of the J SCC-NBS color d esignation, es pecially in field wor k where spee d andease of operation are more important than high accuracy.1.IntroductionThe chroma,In 1941 Nickerson and Newhall published apaper [7]1 en tiLled Central No Lations for !SCC- NBSColor Names based on the first d escription of theISCC- NBS method of describing colors publishedin 1939 [2]. Since then, the ISCC- NBS color-namecharts have been r evised to accord more closely withusage in the textile and other fields and have beenpublished in 1955 under the title The ISCC- NBSM ethod of Designating Colors and a D ictionary ofColor Names [3]. The present paper contains tbecentral notations of tbe r evised color-name blocks.2.Computa tion of CentroidsThe color-name blocks into which the color solidhas been divided are bounded at top and bottom byplanes of cons tan t Munsell value, at two of the sidesby planes of constant Munsell hue, and at t he othertwo sides by concen tric cylindrical surfaces of constant,Munsell clu·oma. The shape of such a block mightbe called a sector of a right cylindrical annulus (like .a piece of pie with the point bitten off). Thesimplest such block is thus defined by six limits :two-value, two-hue, and two-chroma limits; themost complicated of these blocks may be brokendown into three blocks of this simplest or elementaryshape. The general method is to find the centroidof each such block and then find the volume-weightedcentroid of the set of one to three such elementarycentroids.The hue and value of such an elementary centroidare simply the averages of the hue and value limits,respectively. The chroma of the centroid is notentirely a function of the chroma limits, but dependson the number of Munsell-hue steps !1H in the block.Let the cross section of the block at constant Munsellvalue be laid out in cylindrical coordinates with theradius being MUl1sell chroma, 0, and since there are100 Munsell-hue steps in the complete hue circuit, theangle MJ in radians will be given in terms of Munsellhue, H , as 271"!1H/ I00 . Further let H O correspondto the Munsell hue, H, of the centroid of the block.1Figures ill brackets illdieate tbe literature references at tbe end of this·paper.0,of the centroid [1] is defined as:8J Jre.f Jre.0 2 (cos 8)dOd82(j-o c.2 ----,.--- ,o28-2CorOdCd8e.2(0; OxC,, 0 )sin (7I"!1H/ IOO )3(Ox 0 ,,)(7I"!1l-l/ 100),wb ere Ox and On are the upp er and lower chromalimi ts of the block, respectively.By this m ethod, the central notation (H , VIC) ofan elementary block like moderate red, hue ran geIE to 7R, value range from 3.5 to 5.5, and chromarange from 7 to 11 , is determined as:H (lR 7R) /2 4R ; V (3.5 5.5) /2 4.5,andC2 (lP 7 X 11 72) sin (671"/100)3(11 7) (671"/100)2 X 247 X O.1874 913X 18 X O.1885.The central notation of a compound block, that is,one in which two or more elementary blocks arejoined togetber along common constant-hue planes,such as yellowish white or moderate blue, is foundby computing the volume-weighted mean of thecentral notations of the simple blocks. The centroidof a t\yo-component block, for instance, will lie onthe straight line joining the centroids of the component blocks. Therefore, it is necessary to graphthe respective centroids on circular graph paper,connect them by a straight line divided inverselyaccording to the two volumes, and read off the hueand chroma of the resultant centroid. For a threecomponent block , the resultant cen troid for t wo ofthe adjacent blocks is found and then combined bythe same method with the centroid of Lhe thirdblock. The value notation of the resultant centroidi computed as the volume-weighted mean of thevalue notations of the separate centroids.427

3 . Peripheral Color-Name BlocksTABLEThe shape of the psychological color solid may bedescribed as a grossly misshapen grapefruit, set sothat the pithy core is vertical with an irregularouter surface or skin, determined by the MacAdamtheoretical pigment limits [4]. The bounding surface has been determined in Munsell renotationterms by Nickerson and Newhall [8]. This solid,cut into 267 blocks each with a color name attached,forms the ISCC- NBS system of color names. Nowconsider the outermost or peripheral blocks, thosethat extend to the outer surface or skin. Theserepresent colors of maximum saturation, maximumlightness or minimum lightness as determined fromthe MacAdam limits. These peripheral blocks, ofwhich there are 120, have several simple boundarysurfaces (plane and cylindrical) and are closed bythe outer complicated curved surface of the colorsolid . The centroids of these peripheral blocks havebeen estimated graphically by plotting the MacAdam limits on the color-name charts.4. Table of Central Notations of ColorName BlocksIn table 1 the ISCC- NBS color-name blocks areidentified by number and name, and the Munsellrenotation of each centroid is given. The centralnotation of each of the 120 peripheral blocks, lesscertain because it was estimated rather than computed by formula, is marked with an asterisk.The numbers used to identify and order the colordesignations in table 1 are taken from table 1 ofNBS Circular 553 [3]. Thus, for any hue name, theorder of modifiers is vivid; brilliant, strong, deep,very deep; very light, light, moderate, dark, verydark; very pale (very light grayish), pale (lightgrayish), grayish, dark grayish, blackish; -ish white,light -ish gray; -ish gray, dark -ish gray, and -ishblack. Not all of these modifiers are required withevery hue name, as for instance there is no verydark pink: or very pale olive. The notations of thecentroids are given to one decimal place except thatthe value or chroma notations of the centroids ofsome of the peripheral blocks are given as wholenumbers followed by a plus or minus sign, such as4.5 YR 6.8/16 , indicating uncertainty in the nextdecimal place.TABLEC553numbel'1.Central notations of ISCC-NBS colm'-name blocks.ISCC- NBS color nameCentral notationC553number1.Central notations of [SCC- NBS color-nameblocks.- ContinuedISCC- NBS colornameCentral notation12131415vivid redstrong reddeep redvery deep redmoderate red5- R4 / 15 *4.0R 4.5/12.0S.OR 2.8/9.95.0R 1.4/9.0*4.0R 4.5/9.11617181920dark redvery dark redlight grayish redgrayish reddark grayish red4.5R3.5R4.9R4.6R3.5R2.8/6.81.2/4.9*6.0 /3.44.5/4.72.7/2.22122232425blackish redreddish graydark reddish grayreddi sh blackvi vid yellowish pink3.5R6.5R6.0R6.0R8.0R1.1 /1.6*5.5/1.13.5/1.10.9/0.8*7 /13 *2627282930strong yellowish pinkd eep yellowish pinkli ght yellowish pinkmod erate yellowish pinkdark yellowish pink8.0R 7.5/9.0*5.6R 6.0/ 12.40.7YR 8.6/4.8*0.7YR 7.2 /4.87.0R 6 .0/6.03132333435pale yellowish pinkgrayish yellowish pinkbrownish pinkvivid reddish orangestrong reddish orange2.1 YR 8.8/2.2*0.5YR 7.2 /2.36.5YR 7.2 /2.29.5 R 5.5/ 15.5 *9.5R 5.5/ 12.03637383940d eep reddish orangemoderate reddi sh orangedark reddish orangegrayish reddish orangestrong reddish brown9.5R 4.0/12 .09.5R 5.5/9.19.5R 4.0/9.10.5YR 5.5/6.00.5YR 3.0/ 11.2 *4142434445deep reddish brownlight reddish brownmoderate reddish browndark reddish brownlight grayish r eddish brown9.8R l.5 /7.5 *0.5YR 5.5/4.19.6R 3.4/5.29.5R l.3/3.6*3.0YR 5.5/2.34647484950grayish reddish browndark grayish reddish brownvivid orangebrilliant orangestrong orange9.9R 3.4/2.39.5R 2.0/2.04.5 YR 6.6/16 *4.5YR 8.0/12.1 *4.5YR 6.5/ 12 .15152535455deep orangelight orangemoderate orangebrownish orangestrong brown4.5YR4.5YR4.6YR4.5YR5.0YR5.0/12.18 /8.1 *6.5/8.15.0/8.23.5 /8 *5657585960deep brownlight brownmoderate browndark brownlight grayish brown5.0YR5.5YR5.5YR5.5YR6.5YR2.l /6 *5.5/4.63.5/3.91.6/3.6*5.5/2.21112345vivid pinkstrong pinkdeep pinklight pinkmoderate pink1.5R1.5R1.9R2.5R2.5R7 / 13 *7.5/9.1 *6.0/ 11.18.6/5.2*7.2/5.26162636465grayish browndark grayish brownlight brownish graybrownish graybrownish black5.6YR5.5} R6.8YR6.4YR7.5} R3.5/2.02.0/ 1.75.5/ 1.03.5/0.90.8/0.8*678910dark pinkpale pinkgrayish pinkpinkish whitepinkish gray2.5R2.5R2.5R7.6R7.6R6.0/6.08.8/2.3*7 .2/2.39.2/1.0*7.5/1.06667686970vivid orange yellowbrilliant orange yellowstrong orange yellowdeep orange yellowlight orange yellow9.0YR9.0YR9.0 Y R9.0YR9.0YR7.2 /16 *8.4/ 12.1 *7.2/ 12.16.0 / 12.18.6/8 .1 *428