1、 ISO 2017 Graphic technology Spectral measurement and colorimetric computation for graphic arts images Technologie graphique Mesurage spectral et calcul colorimtrique relatifs aux images dans les arts graphiques INTERNATIONAL STANDARD ISO 13655 Third edition 2017-07 Reference number ISO 13655:2017(E
2、) ISO 13655:2017(E)ii ISO 2017 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2017, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including pho
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4、22 749 01 11 Fax +41 22 749 09 47 copyrightiso.org www.iso.org ISO 13655:2017(E)Foreword v Introduction vi 1 Scope . 1 2 Normative references 1 3 T erms and definitions . 1 4 Spectral measurement requirements 4 4.1 Instrument standardization and adjustment . 4 4.2 Reflectance factor measurement . 4
5、4.2.1 Wavelength range, wavelength interval and bandwidth . 4 4.2.2 Illumination requirements and measurement conditions 5 4.2.3 Sample backing material . 7 4.2.4 Measurement geometry 7 4.2.5 Data reporting 7 4.3 Transmittance factor measurement . 8 4.3.1 Wavelength range, wavelength interval and ba
6、ndwidth . 8 4.3.2 Measurement geometry 8 4.3.3 Illumination requirements and measurement conditions 8 4.3.4 Resolution and data reporting . 8 4.4 Self-luminous displays (spectral radiance) measurement 9 4.4.1 Wavelength range, wavelength interval and bandwidth . 9 4.4.2 Measurement geometry 9 4.4.3
7、Polarization 9 4.4.4 Resolution and data reporting 10 5 Colorimetric computation requirements 10 5.1 Calculation of tristimulus values for reflecting and transmitting samples 10 5.1.1 General.10 5.1.2 Calculations with data having 5 nm interval and bandwidth 11 5.1.3 Calculations with data having 10
8、 nm interval and bandwidth .11 5.1.4 Calculations with data having other intervals and bandwidth .11 5.2 Calculation of tristimulus values for self-luminous displays .11 5.3 CIE 1976 (L*a*b*) colour space; CIELAB colour space .13 5.3.1 General.13 5.3.2 CIELAB colour space formulae .13 5.3.3 CIE 1976
9、 colour difference formulae 14 5.3.4 CIEDE2000 colour difference formulae 14 6 Measurement data reporting requirements 15 6.1 Required information .15 6.2 Recommended information 15 6.3 Electronic data reporting 15 Annex A (normative) Sample backing 16 Annex B (informative) Geometry 21 Annex C (info
10、rmative) Improving inter-instrument agreement .24 Annex D (informative) C ertified r efer enc e mat erials (CRMs) .26 Annex E (informative) Procedures for widening the bandwidth .28 Annex F (informative) Fluorescent specimens .30 Annex G (normative) Test method for UV-cut conformance .32 Annex H (in
11、formative) Special cases: Use of polarization .34 ISO 2017 All rights reserved iii Contents Page ISO 13655:2017(E)Annex I (informative) Example computations for converting spectral measurements to tristimulus values .35 Annex J (normative) C omputation of the CIELAB t otal c olour differ enc e (E*ab
12、) 41 Annex K (normative) C omputation of the CIEDE2000 t otal c olour differ enc e (E 00 ) .42 Annex L (informative) Impact of measurement band pass on spectral quantities .46 Bibliography .48 iv ISO 2017 All rights reserved ISO 13655:2017(E) Foreword ISO (the International Organization for Standard
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19、 iso/ foreword .html. This document was prepared by Technical Committee ISO/TC 130, Graphic technology, in collaboration with Technical Committee ISO/TC 42, Photography. This third edition cancels and replaces the second edition (ISO 13655:2009), which has been technically revised to: clarify the re
20、quirements of measurement mode M1; restrict the use of unnecessarily wide bandpass and sampling intervals; provide more realistic specification for the optical properties of a white backing material; restrict the adjustment method of predicting the fluorescent reflectance factor to UV activated subs
21、trates. ISO 2017 All rights reserved v ISO 13655:2017(E) Introduction There are many choices allowed when making spectral measurements and performing colorimetric computations. The specific choices made can result in different numerical values for the same property for the same sample. Thus, it migh
22、t not be possible to make valid comparisons unless the data being compared are all based on the same set of measurement and computational choices. The purpose of this document is to specify a limited number of such choices for the measurement and computation of the colorimetric characteristics of gr
23、aphic arts images and specimens, such as test charts, to allow valid and comparable data to be obtained. While this document references ISO 3664, the International Standard established for viewing conditions in graphic arts and photography, it is not expected that measured colorimetric data will pro
24、vide an absolute correlation with visual colour appearance. When the prior revision of this document was started, it was observed that almost all graphic arts specimens exhibited fluorescence. In most cases, this was due to optical brightening agents (OBA) contained in the paper substrates. In rare
25、cases, the printing inks were fluorescent. According to the recommendations of the 1996 version of this document, this would have meant that the source used for the measurements (i.e. the spectral power distribution of the specimen illumination) was required to closely match CIE illuminant D50. Yet
26、when the 2009 revision was started, not a single colour-measuring instrument sold for the graphic arts market provided an illumination system that closely matched CIE illuminant D50. Instead, most instruments used incandescent lamps for light sources. The spectral power distributions of such lamps h
27、ave varying amounts of UV content. The variation in UV content between instruments could easily amount to a colour difference of 5 b* when measuring substrates with a high level of optical brightening agents. Consequently, the measurement results for unprinted paper substrates and lighter colours di
28、ffered appreciably between different instrument models. For a thorough study of fluorescence effects, see CIE Publication 163. It had also been observed that graphic arts viewing booths vary with respect to UV content, even those that comply with the 1996 version of ISO 3664. The practical result wa
29、s that specimens that have nearly identical measured colorimetric properties, at times will not visually match when viewed in the viewing booth, and vice versa. Only part of such discrepancies can be attributed to fluorescence. There can also be metameric effects due to “non-standard” observers and
30、to instrument wavelength errors, in addition to deviations in the measurement source away from CIE D50. Despite these other potential influences, it was deemed important to provide measurement solutions that would minimize the systematic errors introduced by the interaction of paper fluorescence and
31、 variations in the spectral power distribution of the sample illumination. Methods for the correction of instrument errors and procedures for reliable visual evaluation of colour images are outside of the scope of this document. In the 2009 revision, four measurement choices were defined for reflect
32、ive measurements. Measurement condition M0 requires the source illumination to closely match that of illuminant A; this provides consistency with existing instrumentation and ISO 5-3. Measurement condition M1 requires the colorimetry of the specimen illumination to closely match CIE illuminant D50.
33、Measurement condition M2 only requires that the spectral power distribution of the specimen illumination be provided in the wavelength range from 400 nm to at least 700 nm and have no substantial radiation power in the wavelength range below 400 nm (often referred to as “UVCut”). Measurement conditi
34、on M3 has the same sample illumination requirements as M2 and includes a linear polarizer in the influx and efflux portions of the optical path with their principal axes of polarization in the orthogonal or “crossed” orientation. For specimens in which the fluorescence is primarily that of a UV acti
35、vated blue emission, it is possible to use the method of a virtual fluorescent standard reported by Imura of Konica Minolta 2425to determine the total radiance factors for M0, M1 and M2 conditions. In this revision, Annex A has been revised providing a slightly narrower and more realistic set of spe
36、ctral tolerances on the white backing materials. The properties of the white backing material are critical to reproducibility of readings of packaging printing on clear or translucent films. Finally, as the CIE has been recommending the use of 5 nm intervals for practical tristimulus integration sin
37、ce the second revision of CIE Publication 15 and as graphic images can be composed of colour stimulus functions with very narrow transitions from the low values to the high values, this revision recommends that tristimulus values be based on spectral data collected with a 5 nm interval and a 5 nm ba
38、ndpass. Since many of the instruments now in use in the field are equipped with 10 nm vi ISO 2017 All rights reserved ISO 13655:2017(E) intervals and 10 nm bandpass spectrometers, such readings are allowed with the recommendation that tristimulus calculations be preceded by applying bandpass correct
39、ion to the spectral data as specified in ASTM E2729. The use of instruments with wider sampling intervals and bandpass has been deprecated with the exception of the use of such non-standard instruments to monitor the state of previously characterized materials or objects. The requirements of this do
40、cument are focused on colorimetric measurement equipment intended for use in the graphic arts environment. Helpful information on issues such as substrate backing materials, reporting, standardization, standard and improved colour difference metrics, fluorescence and ways to improve the inter-instru
41、ment agreement are included. These will be useful to technical advisors of graphic arts associations, specialized graphic arts research institutes, and practitioners with an interest in the basics of measurement and process control. ISO 2017 All rights reserved vii Graphic technology Spectral measur
42、ement and colorimetric computation for graphic arts images 1 Scope This document specifies procedures for the measurements and colorimetric computations appropriate to objects that reflect, transmit and emit light, such as flat-panel displays. It also specifies procedures for computation of colorime
43、tric parameters for graphic arts images. Graphic arts include, but are not limited to, the preparation of material for, and volume production by, production printing processes that include offset lithography, letterpress, flexography, gravure, screen and digital printing. This document does not addr
44、ess spectral measurements appropriate to other specific application needs, such as those used during the production of materials, for example, printing paper and proofing media. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content
45、 constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 5-2, Photography and graphic technology Density measurements Part 2: Geometric conditions fo
46、r transmittance density ISO 5-4:2009, Photography and graphic technology Density measurements Part 4: Geometric conditions for reflection density ISO 3664, Graphic technology and photography Viewing conditions ISO 11664-1, Colorimetry Part 1: CIE standard colorimetric observers ISO 11664-3, Colorime
47、try Part 3: CIE tristimulus values ISO 11664-4, Colorimetry Part 4: CIE 1976 L*a*b* Colour space ISO 28178, Graphic technology Exchange format for colour and process control data using XML or ASCII text CIE Publication 15:2004, Colorimetry, 3rd ed. CIE Publication 167:2005, Recommended practice for
48、tabulating spectral data for use in colour computations CIE Publication 176:2006, Geometric Tolerances for Colour Measurements 3 T erms a nd definiti ons For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminological databases for use in standardiza
49、tion at the following addresses: IEC Electropedia: available at h t t p :/ www .electropedia .org/ ISO Online browsing platform: available at h t t p :/ www .iso .org/ obp INTERNATIONAL ST ANDARD ISO 13655:2017(E) ISO 2017 All rights reserved 1 ISO 13655:2017(E) 3.1 adopted white spectral radiance distribution as seen by an image capture or measurement device and converted to colour signals that are considered to be perfectly achromatic and to have an observer adaptive luminance factor of unity, i.e. colour signals
