1、Designation: E2214 121E2214 16Standard Practice forSpecifying and Verifying the Performance of Color-Measuring Instruments1This standard is issued under the fixed designation E2214; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1 NOTEReference to Fig. 1 and Fig. 2 and corrections in the table in A1.3.1 were made editorially in September 2013.INT
3、RODUCTIONRecent advances in optics, electronics and documentary standard have resulted in a proliferation ofinstruments for the measurement of color and appearance of materials and objects. These instrumentspossess very good performance but there has been little progress toward standardizing the ter
4、minologyand procedures to quantify that performance. Therefore, the commercial literature and even somedocumentary standards are a mass of confusing terms, numbers and specifications that are impossibleto compare or interpret.Two recent papers in the literature, have proposed terms and procedures to
5、 standardize thespecification, comparison and verification of the level of performance of a color-measuringinstrument.2,3 Following those procedures, those specifications can be compared to product tolerances.This becomes important so that instrument users and instrument makers can agree on how to c
6、ompareor verify, or both, that their instruments are performing in the field as they were designed and testedin the factory.1. Scope1.1 This practice provides standard terms and procedures for describing and characterizing the performance of spectral and filterbased instruments designed to measure a
7、nd compute the colorimetric properties of materials and objects. It does not set thespecifications but rather gives the format and process by which specifications can be determined, communicated and verified.1.2 This practice does not describe methods that are generally applicable to visible-range s
8、pectroscopic instruments used foranalytical chemistry (UV-VIS spectrophotometers). ASTM Committee E13 on Molecular Spectroscopy and Chromatographyincludes such procedures in standards under their jurisdiction.1.2 This standard does not purport to address all of the safety concerns, if any, associate
9、d with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:4D2244 Practice for Calculation of Color Tolerances and Color Diff
10、erences from Instrumentally Measured Color CoordinatesE284 Terminology of AppearanceE1164 Practice for Obtaining Spectrometric Data for Object-Color Evaluation1 This practice is under the jurisdiction of ASTM Committee E12 on Color and Appearance and is the direct responsibility of Subcommittee E12.
11、04 on Color andAppearance Analysis.Current edition approved July 1, 2012Nov. 1, 2016. Published August 2012November 2016. Originally approved in 2002. Last previous edition approved in 20082012as E2214 08E2214 121. DOI: 10.1520/E2214-12E01.10.1520/E2214-16.2 Ladson, J., “Colorimetric Data Comparison
12、 of Bench-Top and Portable Instruments,” AIC Interim Meeting, Colorimetry, Berlin, 1995.3 Rich, D., “Standardized Terminology and Procedures for Specifying and Verifying the Performance of Spectrocolorimeters,” AIC Color 97 Kyoto, Kyoto, 1997.4 For referencedASTM standards, visit theASTM website, ww
13、w.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of wh
14、at changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered th
15、e official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.2 Other Documents:ISO VIM International Vocabulary of Basic and General Terms in Metrology (VIM)55 ISO/IDE/OIML/BIPM, International Vocabulary of Basic and General
16、Terms in Metrology, International Organization for Standardization, Geneva, Switzerland, 1984.E2214 162NIST Technical Note 1297 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results63. Terminology3.1 Definitions of appearance terms in Terminology E284 are applicable to
17、 this practice.3.2 Definitions of metrology terms in ISO, International Vocabulary of Basic and General Terms in Metrology (VIM) areapplicable to this practice.3.3 Definitions of Terms Specific to This Standard:3.3.1 colorimetric spectrometer, nspectrometer, one component of which is a dispersive el
18、ement (such as a prism, grating orinterference filter or wedge or tunable or discrete series of monochromatic sources), that is normally capable of producing as outputcolorimetric data (such as tristimulus values and derived color coordinates or indices of appearance attributes) as well as theunderl
19、ying spectral data from which the colorimetric data are derived.3.3.1.1 DiscussionAt one time, UV-VIS analytical spectrophotometers were used for colorimetric measurements. Today, while instruments intendedfor use in color measurements share many common components with UV-VIS analytical spectrometer
20、s, there are two distinctclasses of instruments. UV-VIS analytical spectrometers are designed to optimize their use in chemometric quantitative analysis,which requires very precise spectral position and very narrow spectral windows and moderate baseline stability. Colorimetricspectrometers are desig
21、ned to optimize their use as simulations of the visual colorimeter or as the source of spectral andcolorimetric information for computer-assisted color matching systems. They allow more tolerance on the spectral scale andspectral window width but demand much more stability in the radiometric scale.3
22、.3.2 inter-instrument agreement, na form of reproducibility the closeness of agreement between the results of measurementsin which two or more instruments from the same manufacturer and model are compared.3.3.3 inter-model agreement, na form of reproducibility in which the measurements of the closen
23、ess of agreement betweenthe results of measurements in which two or more instruments from different manufacturers, or of different but equivalent design,are compared.3.3.3.1 DiscussionModern instruments have such high precision that small differences in geometric and spectral design can result in si
24、gnificantdifferences in the performance of two instruments. This can occur even though both instruments exhibit design and performancebias which are well within the expected combined uncertainty of the instrument and within the requirements of any internationalstandard.3.3.4 mean color difference fr
25、om the mean, MCDM, na measure of expectation value of the performance of a color-measuringinstrument.3.3.4.1 DiscussionMCDM calculates the average color difference between a set of readings and the average of that set of readings. MCDM =average(Ei(average(Lab) Labi), for i = 1 to N readings. Any sta
26、ndard color difference or color tolerance equation can be usedas long as the report clearly identifies the equation being used (see Practice D2244).4. Summary of Practice4.1 This practice defines standardized terms for the most common instrument measurement performance parameters(repeatability, repr
27、oducibility, inter-instrument agreement, inter-model instrument agreement, accuracy) and describes a set ofmeasurements and artifacts, with which both the producers and users of color-measuring instruments verify or certify thespecification and performance of color-measuring instruments. Following t
28、his practice can improve communications betweeninstrument manufacturers and instrument users and between suppliers and purchasers of colored materials.5. Significance and Use5.1 In todays commerce, instrument makers and instrument users must deal with a large array of bench-top and portablecolor-mea
29、suring instruments, many with different geometric and spectral characteristics. At the same time, manufacturers ofcolored goods are adopting quality management systems that require periodic verification of the performance of the instruments6 Taylor, Barry N., and Kuyatt, Chris E., Guidelines for Eva
30、luating and Expressing the Uncertainty of NIST Measurement Results, NIST Technical Note 1297, U. S.Government Printing Office, Washington, D. C., 1984.E2214 163that are critical to the quality of the final product. The technology involved in optics and electro-optics has progressed greatly overthe l
31、ast decade. The result has been a generation of instruments that are both more affordable and higher in performance. Whathad been a tool for the research laboratory is now available to the retail point of sale, to manufacturing, to design and to corporatecommunications. New documentary standards hav
32、e been published that encourage the use of colorimeters, spectrocolorimeters,and colorimetric spetrometers in applications previously dominated by visual expertise or by filter densitometers.7 Therefore, it isnecessary to determine if an instrument is suitable to the application and to verify that a
33、n instrument or instruments are workingwithin the required operating parameters.5.2 This practice provides descriptions of some common instrumental parameters that relate to the way an instrument willcontribute to the quality and consistency of the production of colored goods. It also describes some
34、 of the material standardsrequired to assess the performance of a color-measuring instrument and suggests some tests and test reports to aid in verifying theperformance of the instrument relative to its intended application.6. Instrument Performance Parameters6.1 Repeatability Repeatabilityis genera
35、lly the most important specification in a color-measuring instrument. Colorimetry isprimarily a relative or differential measurement, not an absolute measurement. In colorimetry, there is always a standard and a trialspecimen. The standard may be a real physical specimen or it may be a set of theore
36、tical target values. The trial is usually similarto the standard in both appearance and spectral nature. Thus, industrial colorimetry is generally a test of how well the instrumentrepeats its readings of the same or nearly the same specimen over a period of minutes, hours, days, and weeks.6.1.1 The
37、ISO VIM defines repeatability as a measure of the random error of a reading and assumes that the sample standarddeviation is an estimate of repeatability. Repeatability is further defined as the standard deviation of a set of measurements takenover a specified time period by a single operator, on a
38、single instrument with a single specimen. This definition is similar to thatin Terminology E284, except that the ISO explicitly defines the metric of “closeness of agreement” as the sample standarddeviation. Since color is a multidimensional property of a material, repeatability should be reported i
39、n terms of themultidimensional variancecovariance matrix.6.1.2 The time period over which the readings are collected must be specified and is often qualitatively described as “short,”“medium,” or “long.” The definitions of these time frames do not overlap. This is intentional, providing clearly defi
40、ned milestonesin the temporal stability of test results.6.1.2.1 For the purposes of colorimetry, “short” is normally the time required to collect a set of 30 readings, taken as fast asthe instrument will allow. The actual time will vary as a function of lamp and power supply characteristics but shou
41、ld be less thanone hour.6.1.2.2 “Medium” term is normally defined as, at least the period of one work shift (8 h) but less than three work shifts (oneday).6.1.2.3 “Long” term is open ended but is often described as any set readings taken over a period of at least 4 to 8 weeks. Thelongest known repor
42、ted study described readings taken over a period of 314 years.86.2 Reproducibility is the second most important specification in a color-measuring instrument. According to TerminologyE284, reproducibility is a form of repeatability the closeness of agreement of the results of measurements in which o
43、ne or moreof the measurement parameters have been systematically changed. Thus the sample is different, the procedures or instrument aredifferent, or the time frame is very long. The increase of disorder over a very long time changes the instrument systematically andthe set of readings really compar
44、es a “young” instrument with an “old” instrument.6.2.1 The ISO VIM defines reproducibility as a type of repeatability the closeness of agreement of the results of measurementsin which either the time frame is very long, in which the operator changes, the instrument changes, or the measurement condit
45、ionschange. ISO again recommends estimating this with a standard deviation. Reproducibility is further defined as the standarddeviation of a set of measurements taken over a specified period of time by a single operator, on a single instrument with a singlespecimen. This definition is similar to tha
46、t in Terminology E284, except that the ISO again, explicitly defines the metric of“closeness of agreement” as the sample standard deviation. Again, since color is a multidimensional property of a material,reproducibility should be reported in terms of the multidimensional variancecovariance matrix.6
47、.2.2 The time period over which the readings are collected must be specified. For the purposes of colorimetry, “long” termrepeatability is the most common and important type of reproducibility. Repeatability and reproducibility have traditionally beenevaluated in colorimetry by comparing the color d
48、ifferences of a set of readings to a single reading or to the average of the set ofreadings.6.3 Inter-Instrument Agreement, as defined in 3.3.2, describes the reproducibility between two or more instruments, of identicaldesign. The ISO has no definition or description of such a concept. This is beca
49、use in most test results, a method or instrumentdependent bias can be assessed. In this situation, such a test measures the consistency of the design and manufacturing process.7 ISO 13655 Spectral Measurement and Colorimetric Computation for Graphic Arts Images, International Organization for Standardization, Geneva, Switzerland.8 Rich, D. C., Battle, D., Malkin, F., Williamson, C., Ingleson, A., “Evaluation of the Long-Term Repeatability of Reflectance Spectrophotometers,” Spectrophotometry,Luminescence and Colour: Science and Compliance, C. Burgess and D.
