ASTM_E_1541_-_98.pdf

Designation:E 1541 98Standard Practice forSpecifying and Matching Color Using the ColorcurveSystem1This standard is issued under the fixed designation E 1541;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.INTRODUCTIONThe COLORCURVEt System2provides a systematic array of color samples whose arrangementhas a simple relationship to the international CIE 1964 system,described in Test Method E 308 andused widely in industry to specify color and color differences from instrumental measurements.Thesystem is based on four main elements:(1)aim points displayed on CIE(CIELAB)a*,b*planes atconstant L*;(2)atlases containing physical representations of those aim points;(3)tables of spectraland colorimetric data for those aim points;and(4)computational methods and computer software thatfurnish Colorcurve notations and reflectances when CIE data are entered,or tristimulus values andreflectance data when Colorcurve notations are entered.The tristimulus data can be used in colorformulation software to formulate specimens with minimum metamerism to the atlas samples.The Master Atlas consists of 1231 atlas samples approximating the computed aim points and thecorresponding data tables.Aseparate Gray and PastelAtlas contains 956 additional samples,for a totalof 2187 unique samples.1.Scope1.1 This practice provides a means for specifying the colorsof objects in terms of the Colorcurve system.Both computa-tional and visual methods are included.This practice isapplicable to inked,painted,dyed,or mass-colored surfacesviewed by an observer with normal color vision.1.2 This practice includes a method for producing a colorspecimen to match a Colorcurve sample.1.3 This practice does not cover the preparation of speci-mens.If specimen preparation is required in conjunction withthis practice,a mutually agreed upon procedure shall beestablished.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D 1729 Practice for Visual Appraisal of Color and ColorDifferences of Diffusely-Illuminated Opaque Materials3E 284 Terminology of Appearance3E 308 Practice for Computing the Colors of Objects byUsing the CIE System3E 1164 Practice for Obtaining Spectrophotometric Data forObject-Color Evaluation33.Terminology3.1 Definitions of appearance terms in Terminology E 284are applicable to this practice.3.2 Definitions:3.2.1 chromaticness,nthe attribute of visual sensationcombining the hue and saturation.3.2.2 hue,nthe attribute of color perception by means ofwhich an object is judged to be red,yellow,green,blue,purple,or intermediate between some adjacent pair of these,consid-ered in a closed ring(red and purple being an adjacent pair).3.3 Definitions of Terms Specific to This Standard:3.3.1Colorcurve atlas,nphysical exemplification of theColorcurve system,consisting of a three-dimensional array of2187 samples displayed on CIELAB cartesian coordinates intwo atlases.3.3.2 Colorcurve system,na color order system based onthe CIE 1964 space,which uses the CIELAB L*lightness scale(L*5 L)and in which chromaticity is represented byopponent-color scales R/G(reds-greens)and Y/B(yellows-blues).1This practice is under the jurisdiction of ASTM Committee E-12 on Color andAppearance and is the direct responsibility of Subcommittee E12.07 on Color OrderSystems US Tag ISO TC 187.Current edition approved Dec.10,1998.Published March 1999.Originallypublished as E 1541 93.Last previous edition E 1541 94.2Colorcurvet is a registered U.S.trademark used by ASTM under the authori-zation of Colorcurve Systems,Inc.Aspects of Colorcurve technology are covered byU.S.Patent 5 012 482.3Annual Book of ASTM Standards,Vol 06.01.1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,West Conshohocken,PA 19428Reprinted from the Annual Book of ASTM Standards.Copyright ASTM3.3.3 lattice scaling constant,nratio of the distance be-tween adjacent samples at a system boundary(CIELABchroma C*5 60 for a major or minor hue axis)and thedistance between the major and adjacent minor hue axes.In theColorcurve system,this is 1/7.3.3.4 major hue axis,nin the Colorcurve system,centralvertical or horizontal axis,that is,a line of sample points whosenotations contain only a single hue term,for example,L45 R3.3.3.5 minor hue axis,n in the Colorcurve system,centraldiagonal axis,that is,a line of sample points whose notationscontain two hue terms in the same amounts,for example,L45R3Y3.4.Summary of Practice4.1 Visual Method of Determining Colorcurve NotationsColorcurve atlas samples are used as