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【英文标准名称】:StandardPracticeforCalculationofColorTolerancesandColorDifferencesfromInstrumentallyMeasuredColorCoordinates
【原文标准名称】:仪器测量颜色坐标中允许色差和色差的计算用标准实施规程
【标准号】:ASTMD2244-2011
【标准状态】:现行
【国别】:
【发布日期】:2011
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:E12.04
【标准类型】:(Practice)
【标准水平】:()
【中文主题词】:颜色;色差;色差度量;色空间;颜色容差
【英文主题词】:color;colordifference;colormetrics;colorspaces;colortolerances
【摘要】:TheoriginalCIEcolorscalesbasedontristimulusvaluesX,Y,Zandchromaticitycoordinatesx,yarenotuniformvisually.EachsubsequentcolorscalebasedonCIEvalueshashadweightingfactorsappliedtoprovidesomedegreeofuniformitysothatcolordifferencesinvariousregionsofcolorspacewillbemorenearlycomparable.Ontheotherhand,colordifferencesobtainedforthesamespecimensevaluatedindifferentcolor-scalesystemsarenotlikelytobeidentical.Toavoidconfusion,colordifferencesamongspecimensortheassociatedtolerancesshouldbecomparedonlywhentheyareobtainedforthesamecolor-scalesystem.Thereisnosimplefactorthatcanbeusedtoconvertaccuratelycolordifferencesorcolortolerancesinonesystemtodifferenceortoleranceunitsinanothersystemforallcolorsofspecimens.Foruniformityofpractice,theCIErecommendedin1976theuseoftwocolormetrics.TheCIELABmetric,withitsassociatedcolor-differenceequation,hasfoundwideacceptanceinthecoatings,plastics,textilesandrelatedindustries.WhiletheCIELABequationhasnotcompletelyreplacedtheuseofHunterLH,aH,bH,thisolderscaleisnolongerrecommendedforotherthanlegacyusers,andisthereforeincludedinanAppendixforhistoricalpurposes.TheCIELABcolor-differenceequationisalsonotrecommendedinthispracticeforuseindescribingsmallandmoderatecolordifferences(differenceswithmagnitudelessthan5.0x0394;E*abunits).Thefourmorerecentlydefinedequations,documentedhere,arehighlyrecommendedforusewithcolor-differencesintherangeof0.0to5.0x0394;E*abunits.Usersofcolortoleranceequationshavefoundthat,ineachsystem,summationofthree,vectorcolor-differencecomponentsintoasinglescalarvalueisveryusefulfordeterminingwhetheraspecimencoloriswithinaspecifiedtolerancefromastandard.However,forcontrolofcolorinproduction,itmaybenecessarytoknownotonlythemagnitudeofthedeparturefromstandardbutalsothedirectionofthisdeparture.Itispossibletoincludeinformationonthedirectionofasmallcolordifferencebylistingthethreeinstrumentallydeterminedcomponentsofthecolordifference.Selectionofcolortolerancesbasedoninstrumentalvaluesshouldbecarefullycorrelatedwithavisualappraisaloftheacceptabilityofdifferencesinhue,lightness,andsaturationobtainedbyusingPracticeD1729.Thethreetoleranceequationsgivenherehavebeentestedextensivelyagainstsuchdatafortextilesandplasticsandhavebeenshowntoagreewiththevisualevaluationstowithintheexperimentaluncertaintyofthevisualjudgments.Thatimpliesthattheequationsthemselvesmisclassifyacolordifferencewithafrequencynogreaterthanthatofthemostexperiencedvisualcolormatcher.Whilecolordifferenceequationsandcolortoleranceequationsareroutinelyappliedtoawiderangeofilluminants,theyhavebeenderivedoroptimized,orboth,foruseunderdaylightillumination.Goodcorrelationwiththevisualjudgmentsmaynotbeobtainedwhenthecalculationsaremadewithotherilluminants.Useofatoleranceequationforotherthandaylightconditionswillrequirevisualconfirmationofthelevelofmetamerisminaccordancewith........
【中国标准分类号】:
【国际标准分类号】:17_180_20
【页数】:12P.;A4
【正文语种】: