Designation:E2970−15StandardPracticeforSpecifyingColorbytheNaturalColourSystem(NCS)1ThisstandardisissuedunderthefixeddesignationE2970;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1TheNaturalColourSystem(NCS)(see1.7)providesacolornotationsystemthatcanbeusedtocommunicatecolor.ThispracticeintroducestheNaturalColourSystem,itsterminology,andconversiontoandfromCIEtristimulusvalues.1.2Thesystemdescribedinthisstandardincludescolorperceptsthatappeartobelongtothesurfaceofamaterial,providedthesurfaceisnotperceivedtobefluorescentortoexhibitdirectionalcoloreffects.1.3Thesystemdoesnotincludecolorsthatappeartobelongtotranslucentorluminescentobjects(so-calledvolumecolorsandluminouscolors),nordoesitincludeothervisualproper-tiesofthesurfacelayer,suchasglossandtexture.AnNCSnotationdoesnotdescribethephysicalorchemicalpropertiesofanobject.1.4ThispracticealsospecifiestheconditionsforvisualorinstrumentaldeterminationoftheNCSnotationofacolorsample,definestherelationshipsbetweenpsychometricallydeterminedNCSnotationsandthecorrespondingCIEcolorcoordinateswhicharetobeusedinthiscontext.1.5FortheaccuracyrequirementsassociatedwithNCSstandardsandNCScolorsamples,theuserisreferredtoSwedishStandardSS19104.Thecoloredillustrationsinthisstandardshallnotbeusedasstandardcolorsamplesinanyway.ColorillustrationsthatareshownonscreenorinprintoutsmaybesignificantlydifferentthantheoriginalNCScolorsampleswiththesameNCSNotationduetolimitedcolorreproductioncapabilitiesinscreensandprinters.1.6ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.7Acknowledgement—NCS,NaturalColourSystemisatrademarkoftheNCSColourABStockholm,Swedenandisprotectedbycopyright(www.ncscolour.com).Allrightsre-served.OriginalNCScolorsamplesareonlyavailableformNCSColourABor...
