SIST EN ISO/CIE 11664-1:2019
(Main)Colorimetry - Part 1: CIE standard colorimetric observers (ISO/CIE 11664-1:2019)
Colorimetry - Part 1: CIE standard colorimetric observers (ISO/CIE 11664-1:2019)
This document specifies colour-matching functions for use in colorimetry. Two sets of colour-matching functions are specified.
— Colour-matching functions for the CIE 1931 standard colorimetric observer.
This set of colour-matching functions is representative of the colour-matching properties of observers with normal colour vision for visual field sizes of angular subtense from about 1° to about 4°, for vision at photopic levels of adaptation.
— Colour-matching functions for the CIE 1964 standard colorimetric observer.
This set of colour-matching functions is representative of the colour-matching properties of observers with normal colour vision for visual field sizes of angular subtense greater than about 4°, for vision at sufficiently high photopic levels and with spectral power distributions such that no participation of the rod receptors of the retina is to be expected.
Farbmetrik - Teil 1: CIE farbmetrische Normalbeobachter (ISO/CIE 11664-1:2019)
Dieses Dokument legt Spektralwertfunktionen zur Anwendung in der Farbmetrik fest. Es werden zwei Sätze von Spektralwertfunktionen festgelegt.
a) Spektralwertfunktionen für den CIE 1931 farbmetrischen Normalbeobachter.
Dieser Satz von Spektralwertfunktionen ist repräsentativ für die vergleichende Farbbewertung von Beobachtern mit normalem Farbsehvermögen für Gesichtsfeldgrößen von etwa 1° bis etwa 4°, bei Adaption des Auges an photopisches Sehen (Tagessehen).
b) Spektralwertfunktionen für den CIE 1964 farbmetrischen Normalbeobachter.
Dieser Satz von Spektralwertfunktionen ist repräsentativ für die vergleichende Farbbewertung von Beobachtern mit normalem Farbsehvermögen für Gesichtsfeldgrößen über etwa 4°, bei Adaption des Auges an photopisches Sehen (Tagessehen) mit ausreichend hohem Strahlungsniveau und mit einer solchen spektralen Strahlungsverteilung, das keine Beteiligung von Stäbchenrezeptoren der Netzhaut zu erwarten ist.
Colorimétrie - Partie 1: Observateurs CIE de référence pour la colorimétrie (ISO/CIE 11664-1:2019)
Le présent document définit des fonctions colorimétriques pour leur emploi en colorimétrie. Deux ensembles de fonctions colorimétriques sont définis.
— Fonctions colorimétriques de l'observateur CIE 1931 de référence pour la colorimétrie.
Cet ensemble de fonctions colorimétriques est représentatif des caractéristiques d'égalisation colorée d'observateurs ayant une vision normale des couleurs, pour un champ visuel d'amplitude angulaire d'environ 1° à environ 4° et pour une vision adaptée au niveau photopique.
— Fonctions colorimétriques de l'observateur CIE 1964 de référence pour la colorimétrie.
Cet ensemble de fonctions colorimétriques est représentatif des caractéristiques d'égalisation colorée d'observateurs ayant une vision normale des couleurs, pour un champ visuel d'amplitude angulaire supérieure à environ 4° et pour une vision à un niveau photopique suffisamment élevé et avec une répartition spectrale d'énergie telle qu'il n'y ait pas lieu de supposer une intervention des bâtonnets rétiniens.
Kolorimetrija - 1. del: Standardizirani barvnometrični opazovalec CIE (ISO/CIE 11664-1:2019)
Ta dokument določa funkcije ujemanja barv za uporabo v kolometriji. Določena sta sklopa
funkcij ujemanja barv.
a) Funkcije ujemanja barv za standardizirani barvnometrični opazovalec CIE 1931.
Ta sklop funkcij ujemanja barv je reprezentativen za lastnosti ujemanja barv opazovalcev z običajnim razlikovanjem barv za velikosti vidnega polja z zornim kotom od pribl. 1° do pribl. 4° za razlikovanje pri prilagoditvi fotopičnih ravni.
a) Funkcije ujemanja barv za standardizirani barvnometrični opazovalec CIE 1964.
Ta sklop funkcij ujemanja barv je reprezentativen za lastnosti ujemanja barv opazovalcev z običajnim razlikovanjem barv za velikosti vidnega polja z zornim kotom, večjim od 4°, za razlikovanje pri dovolj visokih fotopičnih ravneh in s porazdelitvami spektralne moči, tako da se ne pričakuje prisotnosti paličnic v mrežnici.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-september-2019
Nadomešča:
SIST EN ISO 11664-1:2011
Kolorimetrija - 1. del: Standardizirani barvnometrični opazovalec CIE (ISO/CIE
11664-1:2019)
Colorimetry - Part 1: CIE standard colorimetric observers (ISO/CIE 11664-1:2019)
Farbmetrik - Teil 1: CIE farbmetrische Normalbeobachter (ISO/CIE 11664-1:2019)
Colorimétrie - Partie 1: Observateurs CIE de référence pour la colorimétrie (ISO/CIE
11664-1:2019)
Ta slovenski standard je istoveten z: EN ISO/CIE 11664-1:2019
ICS:
17.180.20 Barve in merjenje svetlobe Colours and measurement of
light
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO/CIE 11664-1
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2019
EUROPÄISCHE NORM
ICS 17.180.20 Supersedes EN ISO 11664-1:2011
English Version
Colorimetry - Part 1: CIE standard colorimetric observers
(ISO/CIE 11664-1:2019)
Colorimétrie - Partie 1: Observateurs CIE de référence Farbmetrik - Teil 1: CIE farbmetrische
pour la colorimétrie (ISO/CIE 11664-1:2019) Normalbeobachter (ISO/CIE 11664-1:2019)
This European Standard was approved by CEN on 24 May 2019.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO/CIE 11664-1:2019 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO/CIE 11664-1:2019) has been prepared by Technical Committee CEI
"International Commission on Illumination" in collaboration with Technical Committee CEN/TC 139
“Paints and varnishes” the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2020, and conflicting national standards shall
be withdrawn at the latest by January 2020.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 11664-1:2011.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO/CIE 11664-1:2019 has been approved by CEN as EN ISO/CIE 11664-1:2019 without any
modification.
INTERNATIONAL ISO/CIE
STANDARD 11664-1
First edition
2019-06
Colorimetry —
Part 1:
CIE standard colorimetric observers
Colorimétrie —
Partie 1: Observateurs CIE de référence pour la colorimétrie
Reference number
ISO/CIE 11664-1:2019(E)
©
ISO/CIE 2019
ISO/CIE 11664-1:2019(E)
© ISO/CIE 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
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Published in Switzerland
ii © ISO/CIE 2019 – All rights reserved
ISO/CIE 11664-1:2019(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Specifications . 5
4.1 Colour-matching functions . 5
4.2 Spectral chromaticity coordinates . 5
5 Derivation of the colour-matching functions for the CIE 1931 standard colorimetric
observer . 5
5.1 Experimental basis . 5
5.2 Transformation procedures . 6
5.3 Transformation properties . 6
5.4 Comparison with earlier data . 7
6 Derivation of the colour-matching functions for the CIE 1964 standard colorimetric
observer . 7
6.1 Experimental basis . 7
6.2 Transformation procedures . 7
6.3 Transformation properties . 8
6.4 Comparison with earlier data . 8
7 Practical application of colour-matching functions for CIE standard colorimetric
observers . 8
7.1 Obtaining tristimulus values . 8
7.2 The basis for integration . 9
7.3 Rod activity. 9
7.4 The use of restricted data . 9
7.5 Standard of reflectance . 9
Bibliography .34
© ISO/CIE 2019 – All rights reserved iii
ISO/CIE 11664-1:2019(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by the International Commission on Illumination (CIE) in cooperation
with Technical Committee ISO/TC 274, Light and lighting.
This first edition of ISO/CIE 11664-1 cancels and replaces ISO 11664-1:2007 | CIE S 014-1:2006, of which
it constitutes a minor revision, incorporating minor editorial updates.
A list of all parts in the ISO 11664 and ISO/CIE 11664 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO/CIE 2019 – All rights reserved
ISO/CIE 11664-1:2019(E)
Introduction
Colours with different spectral compositions can look alike. An important function of colorimetry is to
determine whether a pair of such metameric colour stimuli will look alike. The use of visual colorimeters
for this purpose is handicapped by variations in the colour matches made among observers classified as
having normal colour vision. Visual colorimetry also tends to be time-consuming. For these reasons, it
has long been the practice in colorimetry to make use of sets of colour-matching functions to calculate
tristimulus values for colours: equality of tristimulus values for a pair of colours indicates that the colour
appearances of the two colours match, when they are viewed in the same conditions by an observer
for whom the colour-matching functions apply. The use of standard sets of colour-matching functions
makes the comparison of tristimulus values obtained at different times and locations possible.
© ISO/CIE 2019 – All rights reserved v
INTERNATIONAL STANDARD ISO/CIE 11664-1:2019(E)
Colorimetry —
Part 1:
CIE standard colorimetric observers
1 Scope
This document specifies colour-matching functions for use in colorimetry. Two sets of colour-matching
functions are specified.
a) Colour-matching functions for the CIE 1931 standard colorimetric observer.
This set of colour-matching functions is representative of the colour-matching properties of
observers with normal colour vision for visual field sizes of angular subtense from about 1° to
about 4°, for vision at photopic levels of adaptation.
b) Colour-matching functions for the CIE 1964 standard colorimetric observer.
This set of colour-matching functions is representative of the colour-matching properties of
observers with normal colour vision for visual field sizes of angular subtense greater than about
4°, for vision at sufficiently high photopic levels and with spectral power distributions such that no
participation of the rod receptors of the retina is to be expected.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
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.
1)
CIE S 017:—, ILV: International Lighting Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in CIE S 017 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
colour stimulus function
φ (λ)
λ
function describing the spectral distribution of the colour stimulus
Note 1 to entry: The colour stimulus function is generated by the spectral distribution of a radiometric quantity,
such as radiance or radiant flux.
Note 2 to entry: For object colours the colour stimulus function, φ (λ), is equal to the product of the relative
λ
spectral distribution, S(λ), and either the spectral reflectance, ρ(λ), or the spectral radiance factor, β(λ), or the
spectral transmittance, τ(λ), depending on the application.
1) Under preparation. Stage at the time of publication: CIE DIS 017:2016.
© ISO/CIE 2019 – All rights reserved 1
ISO/CIE 11664-1:2019(E)
[SOURCE: CIE S 017:—, entry 17-23-003, modified — The definition has been completely revised and
the notes to entry have been added.]
3.2
metameric colour stimuli, pl
metamers, pl
spectrally different colour stimuli that have the same tristimulus values in a specified colorimetric system
Note 1 to entry: The corresponding property is called “metamerism”.
[SOURCE: CIE S 017:—, entry 17-23-008]
3.3
monochromatic stimulus
spectral stimulus
stimulus consisting of monochromatic radiation
[SOURCE: CIE S 017:—, entry 17-23-011]
3.4
equi-energy spectrum
equal energy spectrum
spectrum of radiation whose spectral distribution of a radiometric quantity as a function of wavelength
is constant throughout the visible region
Note 1 to entry: The radiation of the equi-energy spectrum is sometimes regarded as an illuminant, in which case
it is denoted by the symbol E.
[SOURCE: CIE S 017:—, entry 17-23-023, modified — “(φ (λ) = constant)” at the end of the definition
λ
omitted.]
3.5
additive mixture
stimulation that combines on the retina the actions of various colour stimuli in such a
manner that they cannot be perceived individually
[SOURCE: CIE S 017:—, entry 17-23-030]
3.6
colour matching
action of making a colour stimulus appear the same in colour as a given colour stimulus
[SOURCE: CIE S 017:—, entry 17-23-031]
3.7
trichromatic system
system for specifying colour stimuli in terms of tristimulus values, based on matching colours by
additive mixture of three suitably chosen reference colour stimuli
[SOURCE: CIE S 017:—, entry 17-23-036]
3.8
reference colour stimuli, pl
three colour stimuli on which a trichromatic system is based
Note 1 to entry: These stimuli are either real colour stimuli or theoretical stimuli which are defined by linear
combinations of real colour stimuli.
Note 2 to entry: In the CIE standard colorimetric systems, the reference colour stimuli are represented by the
symbols [R], [G], [B]; [X], [Y], [Z]; [R ], [G ], [B ] or [X ], [Y ], [Z ].
10 10 10 10 10 10
[SOURCE: CIE S 017:—, entry 17-23-037, modified — “set of three" has been changed to “three" and the
"and" has been changed to "or" in Note 2 to entry.]
2 © ISO/CIE 2019 – All rights reserved
ISO/CIE 11664-1:2019(E)
3.9
tristimulus values, pl
amounts of the reference colour stimuli, in a given trichromatic system, required
to match the colour of the stimulus considered
Note 1 to entry: In the CIE standard colorimetric systems, the tristimulus values are represented, for example, by
the symbols R, G, B; X, Y, Z; R , G , B or X , Y , Z .
10 10 10 10 10 10
[SOURCE: CIE S 017:—, entry 17-23-038, modified — “amount of the three reference" has been changed
to "amounts of the reference".]
3.10
colour-matching functions, pl
tristimulus values of monochromatic stimuli of equal radiant flux
[SOURCE: CIE S 017:—, entry 17-23-039, modified — Notes to entry omitted.]
3.11
CIE 1931 standard colorimetric system
X, Y, Z
system for determining the tristimulus values of any spectral power distribution using the set of
reference colour stimuli [X], [Y], [Z], and the three CIE colour-matching functions xy()λλ,,() z()λ
adopted by the CIE in 1931
Note 1 to entry: y()λ is identical to V(λ) and hence the tristimulus values Y are proportional to values of
luminance.
Note 2 to entry: The CIE 1931 standard colorimetric system is applicable to centrally viewed fields of angular
subtense between about 1° and about 4° (0,017 rad and 0,07 rad).
Note 3 to entry: The CIE 1931 standard colorimetric system can be derived from the CIE 1931 RGB colorimetric
system using a transformation based on a set of three linear equations. The CIE 1931 RGB system is based on
three real monochromatic reference stimuli.
Note 4 to entry: See also CIE 15, Colorimetry.
[SOURCE: CIE S 017:—, entry 17-23-045]
3.12
CIE 1964 standard colorimetric system
X , Y , Z
10 10 10
system for determining the tristimulus values of any spectral power distribution using the set of
reference colour stimuli [X ], [Y ], [Z ], and the three CIE colour-matching functions
10 10 10
xyλλ,,z λ adopted by the CIE in 1964
() () ()
10 10 10
Note 1 to entry: The CIE 1964 standard colorimetric system is applicable to centrally viewed fields of angular
subtense greater than about 4° (0,07 rad).
Note 2 to entry: When the CIE 1964 standard colorimetric system is used, all symbols that represent colorimetric
measures are distinguished by use of the subscript 10.
Note 3 to entry: See also CIE 15, Colorimetry.
[SOURCE: CIE S 017:—, entry 17-23-046]
© ISO/CIE 2019 – All rights reserved 3
ISO/CIE 11664-1:2019(E)
3.13
CIE colour-matching functions, pl
functions xyλλ,,z λ in the CIE 1931 standard colorimetric system or xyλλ,,z λ
() () () () () ()
10 10 10
in the CIE 1964 standard colorimetric system
[SOURCE: CIE S 017:—, entry 17-23-047]
3.14
CIE 1931 standard colorimetric observer
ideal observer whose colour-matching properties correspond to the CIE colour-matching functions
xyλλ,,z λ adopted by the CIE in 1931
() () ()
[SOURCE: CIE S 017:—, entry 17-23-049]
3.15
CIE 1964 standard colorimetric observer
ideal observer whose colour-matching properties correspond to the CIE colour-matching functions
xyλλ,,z λ adopted by the CIE in 1964
() () ()
10 10 10
[SOURCE: CIE S 017:—, entry 17-23-050, modified — Note 1 to entry omitted.]
3.16
chromaticity coordinates, pl
coordinates expressing the quotients of each of a set of three tristimulus values to their sum
Note 1 to entry: As the sum of the three chromaticity coordinates is equal to 1, two of them are sufficient to
define a chromaticity.
Note 2 to entry: In the CIE standard colorimetric systems, the chromaticity coordinates are represented by the
symbols x, y, z or x , y , z .
10 10 10
Note 3 to entry: The chromaticity coordinates are a quantity of unit one.
[SOURCE: CIE S 017:—, entry 17-23-053, modified — “ratios” has been changed to “quotients”.]
3.17
spectral chromaticity coordinates, pl
r(λ), g(λ), b(λ); x(λ), y(λ), z(λ); r (λ), g (λ), b (λ); x (λ), y (λ), z (λ)
10 10 10 10 10 10
chromaticity coordinates of monochromatic stimuli
[SOURCE: CIE S 017:—, entry 17-23-055]
3.18
spectral luminous efficiency
V(λ), ; V′(λ), ; V (λ), ; V (λ),
mes;m 10
the CIE 10° photopic photometric observer>; V (λ),
M
efficiency function for photopic vision>
quotient of the radiant flux at wavelength λ and that at
m
wavelength λ, such that both produce equally intense luminous sensations for a specified photometric
condition and λ is chosen so that the maximum value of this quotient is equal to 1
m
[SOURCE: CIE S 017:—, entry 17-21-035, modified — Notes to entry omitted.]
3.19
perfect reflecting diffuser
ideal isotropic diffuser with a reflectance equal to unity
4 © ISO/CIE 2019 – All rights reserved
ISO/CIE 11664-1:2019(E)
4 Specifications
4.1 Colour-matching functions
The colour-matching functions xyλλ,,z λ of the CIE 1931 standard colorimetric observer are
() () ()
defined by the values given in Table 1, and those xyλλ,,z λ of the CIE 1964 standard
() () ()
10 10 10
colorimetric observer are defined by the values given in Table 2. The values are given at 1 nm wavelength
intervals from 360 nm to 830 nm. If values are required at closer wavelength intervals than 1 nm, they
should be derived by linear interpolation.
4.2 Spectral chromaticity coordinates
Tables 1 and 2 also give values for the spectral chromaticity coordinates, x(λ), y(λ), z(λ); x (λ), y (λ),
10 10
z (λ); these have been derived from the appropriate colour-matching functions by forming the ratios
according to Formulae (1) to (6):
x λ
()
x λ = (1)
()
xyλλ+ +z λ
() () ()
y λ
()
y λ = (2)
()
xyλλ+ +z λ
() () ()
z λ
()
z λ = (3)
()
xyλλ+ +z λ
() () ()
and
x λ
()
x λ = (4)
()
xyλλ+ +z λ
() () ()
10 10 10
y λ
()
y λ = (5)
()
xyλλ+ +z λ
() () ()
10 10 10
z λ
()
z ()λ = (6)
xyλλ+ +z λ
() () ()
10 10 10
NOTE All wavelengths are for standard air.
5 Derivation of the colour-matching functions for the CIE 1931 standard
colorimetric observer
5.1 Experimental basis
The CIE 1931 colour-matching functions, xyλλ,,z λ , were derived from experimental work
() () ()
[1][2] [3]
carried out by Wright and Guild in which a total of 17 observers matched the monochromatic
stimuli of the spectrum, over the range of about 400 nm to 700 nm, with additive mixtures of red, green
and blue lights, using observing fields of 2° angular subtense.
© ISO/CIE 2019 – All rights reserved 5
ISO/CIE 11664-1:2019(E)
5.2 Transformation procedures
The experimental results were converted into those that would have been obtained if the matching had
been carried out using, as reference colour stimuli, monochromatic radiations of wavelengths 700 nm
for the red [R], 546,1 nm for the green [G] and 435,8 nm for the blue [B], measured in units such that
equal quantities of [R], [G] and [B] were required to match the equi-energy spectrum.
The results for the 17 observers were averaged and then slightly adjusted so that by adding together
suitable proportions of the [R], [G], [B] colour-matching functions rgλλ,,b λ it was possible to
() () ()
obtain a function identical to that of the CIE spectral luminous efficiency, V(λ); the proportions used
were in the ratios of 1,000 0 to 4,590 7 to 0,060 1, and these were then the relative luminances of unit
quantities of [R], [G] and [B]. The CIE 1931 colour-matching functions were then determined by
Formulae (7) to (9):
xrλλ= 0,490+ ,,31gbλλ+ 020 n (7)
() () () ()
yrλλ= 0,176 97 + 0,,812 40gbλλ+ 0 01063 n (8)
() () () ()
zrλλ= 0,000+ ,,01gbλλ+ 099 n (9)
() () () ()
where
n is a normalizing constant given by Formula (10).
V λ
()
n= (10)
0,176 97rgλλ+ 0,,812 40 + 0 01063b λ
() () ()
n is a constant, not a function of wavelength, because the coefficients 0,176 97, 0,812 40, and
0,010 63 are in the same ratios to one another as the ratio of 1,000 0 to 4,590 7 to 0,060 1; n is
equal to Formula (11).
1,000 0 ++ 4,590 7 0,060 1
= 55,650 8 (11)
0,176 97 ++ 0,812 40 0,010 63
The values of xyλλ,,z λ given in Table 1 from 360 nm to 400 nm and from 700 nm to 830 nm
() () ()
are extrapolations.
5.3 Transformation properties
The transformation given in Formulae (7) to (9) was chosen to achieve the following objectives:
1) The y λ function is identical to the V(λ) function.
()
2) The values of xyλλ,,z λ are all positive for all wavelengths of the spectrum (unlike
() () ()
rgλλ,,b λ , one of which is negative at most wavelengths because of the need to desaturate
() () ()
spectral stimuli when matching them with red, green and blue reference stimuli).
3) The values of z λ are zero for wavelengths longer than 650 nm.
()
6 © ISO/CIE 2019 – All rights reserved
ISO/CIE 11664-1:2019(E)
4) The values of x λ are nearly zero at wavelengths around 505 nm.
()
5) The values of x λ and y λ are small at the short-wavelength end of the spectrum.
() ()
6) The equi-energy spectrum is specified by equal amounts of X, Y and Z.
Because the y λ function is identical to the V(λ) function, the Y tristimulus value is proportional to
()
luminance.
5.4 Comparison with earlier data
The values of xyλλ,,z λ given in Table 1 for the spectral range of 380 nm to 780 nm at 5 nm
() () ()
intervals, when rounded to four decimal places, agree closely with those originally published in 1931.
There are only three minor differences: at λ = 775 nm the new value of x λ is 0,000 1 instead of
()
0,000 0; at λ = 555 nm, y λ = 1,000 0 instead of 1,000 2 and at λ = 740 nm, y λ = 0,000 2 instead of
() ()
0,000 3. These changes are considered insignificant in most colorimetric computations.
When the relative luminances of unit quantities of [R], [G] and [B] are deduced from the data of Table 1,
the values obtained are 1,000 0 to 4,588 8 to 0,060 3 instead of 1,000 0 to 4,590 7 to 0,060 1, the relative
radiances being 71,893 8 to 1,374 7 to 1,000 0 instead of 72,096 2 to 1,379 1 to 1,000 0. These changes
are also considered insignificant in practice.
The values given in CIE 15 at 5 nm intervals agree exactly with those given in Table 1.
6 Derivation of the colour-matching functions for the CIE 1964 standard
colorimetric observer
6.1 Experimental basis
The CIE 1964 colour-matching functions xyλλ,,z λ were derived from experimental
() () ()
10 10 10
[4] [5]
work carried out by Stiles and Burch and by Speranskaya in which a total of 67 observers matched
monochromatic stimuli of the spectrum from approximately 390 nm to 830 nm with additive mixtures
of red, green, and blue lights, using observing fields of 10° angular subtense (but ignoring the central
4° or so).
6.2 Transformation procedures
The experimental results were converted into those that would have been obtained if the matching had
been carried out using, as reference colour stimuli, monochromatic radiations of wavenumbers
−1 −1 −1
15 500 cm for the red [R ], 19 000 cm for the green [G ] and 22 500 cm for the blue [B ],
10 10 10
corresponding approximately to wavelengths 645,2 nm, 526,3 nm and 444,4 nm, respectively. The
units used for the quantities of [R ], [G ] and [B ] were such that equal amounts were required to
10 10 10
match the equi-energy spectrum. A weighted average of the results for the 67 observers was used to
provide a set of colour-matching functions rgνν,,b ν . The CIE 1964 colour-matching
() () ()
10 10 10
functions were then derived using Formulae (12) to (14):
xrνν=0,,341080 +0 189145gbνν+0,387529 (12)
() () () ()
10 10 10 10
yrνν=0,,139058 +0 837460gbνν+0,073316 (13)
() () () ()
10 10 10 10
© ISO/CIE 2019 – All rights reserved 7
ISO/CIE 11664-1:2019(E)
zrνν=0,,000000 +0 039553gbνν+2,026200 (14)
() () () ()
10 10 10 10
In Table 2, the CIE 1964 colour-matching functions xyλλ,,z λ are given on a wavelength
() () ()
10 10 10
basis and were obtained by interpolation from the frequency-based functions given in Formulae (12) to
(14). The values in the range of 360 nm to 390 nm are extrapolations.
6.3 Transformation properties
The transformation given in Formulae (12) to (14) was chosen to achieve a colorimetric system (X ,
Y , Z ) having a coordinate system broadly similar to that of the CIE 1931 (X, Y, Z) system. However, in
10 10
the 1964 system, the data were not constrained to fit the CIE V(λ) spectral luminous efficiency function,
and the Y tristimulus value is not proportional to luminance calculated using the V(λ) function.
6.4 Comparison with earlier data
The values given in CIE 15 at 5 nm intervals agree exactly with those given in Table 2.
7 Practical application of colour-matching functions for CIE standard
colorimetric observers
7.1 Obtaining tristimulus values
The data given in Tables 1 and 2 provide the tristimulus values and chromaticity coordinates of all
monochromatic stimuli directly or by interpolation. For stimuli consisting of radiation of various
wavelengths, the tristimulus values X, Y, Z and X , Y , Z are calculated by integration over the
10 10 10
spectral range 360 nm to 830 nm using Formulae (15) to (20):
Xk= ϕλ x λλd (15)
() ()
λ
∫
λ
Yk= ϕλ y λλd (16)
() ()
λ
∫
λ
Zk= ϕλ z λλd (17)
() ()
λ
∫
λ
Xk= ϕλ x λλd (18)
() ()
10 10 λ 10
∫
λ
Yk= ϕλ y λλd (19)
() ()
10 10 λ 10
∫
λ
Zk= ϕλ z λλd (20)
() ()
10 10 λ 10
∫
λ
where
is the colour stimulus function of the stimulus
φλ
()
λ
considered;
are the appropriate CIE colour-matching functions;
xyλλ,,z λ , xyλλ,,z λ
() () () () () ()
10 10 10
k and k are constants.
8 © ISO/CIE 2019 – All rights reserved
ISO/CIE 11664-1:2019(E)
Tristimulus values are usually evaluated on a relative basis, and the constants, k and k are then chosen
according to agreed conventions; however, it is essential that, for stimuli that will be considered
together, the same value for k (or for k ) be adopted, so that all the tristimulus values involved are
assessed on the same basis. For reflecting object-colours, k and k shall be chosen so that Y and Y are
10 10
equal to 100 for the perfect reflecting diffuser, and, for transmitting object-colours, so that Y and Y
are equal to 100 for the perfect transmitter. In the case of primary light sources, if it is required that Y
be equal to the absolute value of the photometric quantity, k shall be equal to K , the maximum spectral
m
luminous efficacy (which is equal to 683 lm/W) and φλ shall then be the spectral concentration of
()
λ
the radiometric quantity corresponding to the photometric quantity required.
7.2 The basis for integration
The integration step in Formulae (15) to (20) implies additivity of colour matches: that is, if two colour
stimuli [C1] and [C2] have tristimulus values X Y , Z , and X , Y , Z , respectively, then the additive
1 1 1 2 2 2
mixture of [C1] and [C2] will have tristimulus values X + X , Y + Y , Z + Z . Experimental investigations
1 2 1 2 1 2
have shown that, although additivity of this type sometimes fails to occur, the principle of additivity is
sufficiently valid for predicting colour matches in most cases of importance in practical colorimetry.
7.3 Rod activity
The tristimulus values in the CIE 1964 standard colorimetric system are relevant only to those
observing conditions where the luminances are sufficiently high and the spectral power distributions
are such that no significant participation of the rod receptors of the retina is to be expected.
7.4 The use of restricted data
For most practical applications of colorimetry, it is sufficient to use values of colour-matching
functions at less frequent intervals of wavelength than every 1 nm, covering a more restricted range
of wavelengths than from 360 nm to 830 nm, and using fewer decimal places than are given in Tables 1
and 2. Data and guidelines that facilitate such practice are given in CIE 15, together with various other
recommended procedures for practical colorimetry.
7.5 Standard of reflectance
The perfect reflecting diffuser is the CIE reference standard for the colorimetry of reflecting samples.
© ISO/CIE 2019 – All rights reserved 9
ISO/CIE 11664-1:2019(E)
Table 1 — Colour-matching functions and chromaticity coordinates of CIE 1931 standard
colorimetric observer
CIE colour-matching functions Chromaticity coordinates
Wave-
length
x(λ) y(λ) z(λ)
λ (nm) x()λ y()λ z()λ
360 0,000 129 900 0 0,000 003 917 000 0,000 606 100 0 0,175 56 0,005 29 0,819 15
361 0,000 145 847 0 0,000 004 393 581 0,000 680 879 2 0,175 48 0,005 29 0,819 23
362 0,000 163 802 1 0,000 004 929 604 0,000 765 145 6 0,175 40 0,005 28 0,819 32
363 0,000 184 003 7 0,000 005 532 136 0,000 860 012 4 0,175 32 0,005 27 0,819 41
364 0,000 206 690 2 0,000 006 208 245 0,000 966 592 8 0,175 24 0,005 26 0,819 50
365 0,000 232 100 0 0,000 006 965 000 0,001 086 000 0,175 16 0,005 26 0,819 58
366 0,000 260 728 0 0,000 007 813 219 0,001 220 586 0,175 09 0,005 25 0,819 66
367 0,000 293 075 0 0,000 008 767 336 0,001 372 729 0,175 01 0,005 24 0,819 75
368 0,000 329 388 0 0,000 009 839 844 0,001 543 579 0,174 94 0,005 23 0,819 83
369 0,000 369 914 0 0,000 011 043 23 0,001 734 286 0,174 88 0,005 22 0,819 90
370 0,000 414 900 0 0,000 012 390 00 0,001 946 000 0,174 82 0,005 22 0,819 96
371 0,000 464 158 7 0,000 013 886 41 0,002 177 777 0,174 77 0,005 23 0,820 00
372 0,000 518 986 0 0,000 015 557 28 0,002 435 809 0,174 72 0,005 24 0,820 04
373 0,000 581 854 0 0,000 017 442 96 0,002 731 953 0,174 66 0,005 24 0,820 10
374 0,000 655 234 7 0,000 019 583 75 0,003 078 064 0,174 59 0,005 22 0,820 19
375 0,000 741 600 0 0,000 022 020 00 0,003 486 000 0,174 51 0,005 18 0,820 31
376 0,000 845 029 6 0,000 024 839 65 0,003 975 227 0,174 41 0,005 13 0,820 46
377 0,000 964 526 8 0,000 028 041 26 0,004 540 880 0,174 31 0,005 07 0,820 62
378 0,001 094 949 0,000 031 531 04 0,005 158 320 0,174 22 0,005 02 0,820 76
379 0,001 231 154 0,000 035 215 21 0,005 802 907 0,174 16 0,004 98 0,820 86
380 0,001 368 000 0,000 039 000 00 0,006 450 001 0,174 11 0,004 96 0,820 93
381 0,001 502 050 0,000 042 826 40 0,007 083 216 0,174 09 0,004 96 0,820 95
382 0,001 642 328 0,000 046 914 60 0,007 745 488 0,174 07 0,004 97 0,820 96
383 0,001 802 382 0,000 051 589 60 0,008 501 152 0,174 06 0,004 98 0,820 96
384 0,001 995 757 0,000 057 176 40 0,009 414 544 0,174 04 0,004 98 0,820 98
385 0,002 236 000 0,000 064 000 00 0,010 549 99 0,174 01 0,004 98 0,821 01
386 0,002 535 385 0,000 072 344 21 0,011 965 80 0,173 97 0,004 97 0,821 06
387 0,002 892 603 0,000 082 212 24 0,013 655 87 0,173 93 0,004 94 0,821 13
388 0,003 300 829 0,000 093 508 16 0,015 588 05 0,173 89 0,004 93 0,821 18
389 0,003 753 236 0,000 106 136 1 0,017 730 15 0,173 84 0,004 92 0,821 24
390 0,004 243 000 0,000 120 000 0 0,020 050 01 0,173 80 0,004 92 0,821 28
391 0,004 762 389 0,000 134 984 0 0,022 511 36 0,173 76 0,004 92 0,821 32
392 0,005 330 048 0,000 151 492 0 0,025 202 88 0,173 70 0,004 94 0,821 36
393 0,005 978 712 0,000 170 208 0 0,028 279 72 0,173 66 0,004 94 0,821 40
394 0,006 741 117 0,000 191 816 0 0,031 897 04 0,173 61 0,004 94 0,821 45
395 0,007 650 000 0,000 217 000 0 0,036 210 00 0,173 56 0,004 92 0,821 52
396 0,008 751 373 0,000 246 906 7 0,041 437 71 0,173 51 0,004 90 0,821 59
397 0,010 028 88 0,000 281 240 0 0,047 503 72 0,173 47 0,004 86 0,821 67
398 0,011 421 70 0,000 318 520 0 0,054 119 88 0,173 42 0,004 84 0,821 74
399 0,012 869 01 0,000 357 266 7 0,060 998 03 0,173 38 0,004 81 0,821 81
10 © ISO/CIE 2019 – All rights reserved
ISO/CIE 11664-1:2019(E)
Table 1 (continued)
CIE colour-matching functions Chromaticity coordinates
Wave-
length
x(λ) y(λ) z(λ)
λ (nm) x()λ y()λ z()λ
400 0,014 310 00 0,000 396 000 0 0,067 850 01 0,173 34 0,004 80 0,821 86
401 0,015 704 43 0,000 433 714 7 0,074 486 32 0,173 29 0,004 79 0,821 92
402 0,017 147 44 0,000 473 024 0 0,081 361 56 0,173 24 0,004 78 0,821 98
403 0,018 781 22 0,000 517 876 0 0,089 153 64 0,173 17 0,004 78 0,822 05
404 0,020 748 01 0,000 572 218 7 0,098 540 48 0,173 10 0,004 77 0,822 13
405 0,023 190 00 0,000 640 000 0 0,110 200 0 0,173 02 0,004 78 0,822 20
406 0,026 207 36 0,000 724 560 0 0,124 613 3 0,172 93 0,004 78 0,822 29
407 0,029 782 48 0,000 825 500 0 0,141 701 7 0,172 84 0,004 79 0,822 37
408 0,033 880 92 0,000 941 160 0 0,161 303 5 0,172 75 0,004 80 0,822 45
409 0,038 468 24 0,001 069 880 0,183 256 8 0,172 66 0,004 80 0,822 54
410 0,043 510 00 0,001 210 000 0,207 400 0 0,172 58 0,004 80 0,822 62
411 0,048 995 60 0,001 362 091 0,233 692 1 0,172 49 0,004 80 0,822 71
412 0,055 022 60 0,001 530 752 0,262 611 4 0,172 39 0,004 80 0,822 81
413 0,061 718 80 0,001 720 368 0,294 774 6 0,172 30 0,004 80 0,822 90
414 0,069 212 00 0,001 935 323 0,330 798 5 0,172 19 0,004 82 0,822 99
415 0,077 630 00 0,002 180 000 0,371 300 0 0,172 09 0,004 83 0,823 08
416 0,086 958 11 0,002 454 800 0,416 209 1 0,171 98 0,004 86 0,823 16
417 0,097 176 72 0,002 764 000 0,465 464 2 0,171 87 0,004 89 0,823 24
418 0,108 406 3 0,003 117 800 0,519 694 8 0,171 74 0,004 94 0,823 32
419 0,120 767 2 0,003 526 400 0,579 530 3 0,171 59 0,005 01 0,823 40
420 0,134 380 0 0,004 000 000 0,645 600 0 0,171 41 0,005 10 0,823 49
421 0,149 358 2 0,004 546 240 0,718 483 8 0,171 21 0,005 21 0,823 58
422 0,165 395 7 0,005 159 320 0,796 713 3 0,170 99 0,005 33 0,823 68
423 0,181 983 1 0,005 829 280 0,877 845 9 0,170 77 0,005 47 0,823 76
424 0,198 611 0 0,006 546 160 0,959 439 0 0,170 54 0,005 62 0,823 84
425 0,214 770 0 0,007 300 000 1,039 050 1 0,170 30 0,005 79 0,823 91
426 0,230 186 8 0,008 086 507 1,115 367 3 0,170 05 0,005 97 0,823 98
427 0,244 879 7 0,008 908 720 1,188 497 1 0,169 78 0,006 18 0,824 04
428 0,258 777 3 0,009 767 680 1,258 123 3 0,169 50 0,006 40 0,824 10
429 0,271 807 9 0,010 664 43 1,323 929 6 0,169 20 0,006 64 0,824 16
430 0,283 900 0 0,011 600 00 1,385 600 0 0,168 88 0,006 90 0,824 22
431 0,294 943 8 0,012 573 17 1,442 635 2 0,168 53 0,007 18 0,824 29
432 0,304 896 5 0,013 582 72 1,494 803 5 0,168 15 0,007 49 0,824 36
433 0,313 787 3 0,014 629 68 1,542 190 3 0,167 75 0,007 82 0,824 43
434 0,321 645 4 0,015 715 09 1,584 880 7 0,167 33 0,008 17 0,824 50
435 0,328 500 0 0,016 840 00 1,622 960 0 0,166 90 0,008 55 0,824 55
436 0,334 351 3 0,018 007 36 1,656 404 8 0,166 45 0,008 96 0,824 59
437 0,339 210 1 0,019 214 48 1,685 295 9 0,165 98 0,009 40 0,824 62
438 0,343 121 3 0,020 453 92 1,709 874 5 0,165 48 0,009 87 0,824 65
439 0,346 129 6 0,021 718 24 1,730 382 1 0,164 96 0,010 35 0,824 69
440 0,348 280 0 0,023 000 00 1,747 060 0 0,164 41 0,010 86 0,824 73
441 0,349 599 9 0,024 294 61 1,760 044 6 0,163 83 0,011 38 0,824 79
© ISO/CIE 2019 – All rights reserved 11
ISO/CIE 11664-1:2019(E)
Table 1 (continued)
CIE colour-matching functions Chromaticity coordinates
Wave-
length
x(λ) y(λ) z(λ)
λ (nm) x()λ y()λ z()λ
442 0,350 147 4 0,025 610 24 1,769 623 3 0,163 21 0,011 94 0,824 85
443 0,350 013 0 0,026 958 57 1,776 263 7 0,162 55 0,012 52 0,824 93
444 0,349 287 0 0,028 351 25 1,780 433 4 0,161 85 0,013 14 0,825 01
445 0,348 060 0 0,029 800 00 1,782 600 0 0,161 11 0,013 79 0,825 10
446 0,346 373 3 0,031 310 83 1,782 968 2 0,160 31 0,014 49 0,825 20
447 0,344 262 4 0,032 883 68 1,781 699 8 0,159 47 0,015 23 0,825 30
448 0,341 808 8 0,034 521 12 1,779 198 2 0,158 57 0,016 02 0,825 41
449 0,339 094 1 0,036 225 71 1,775 867 1 0,157 63 0,016 84 0,825 53
450 0,336 200 0 0,038 000 00 1,772 110 0 0,156 64 0,017 71 0,825 65
451 0,333 197 7 0,039 846 67 1,768 258 9 0,155 60 0,018 61 0,825 79
452 0,330 041 1 0,041 768 00 1,764 039 0 0,154 52 0,019 56 0,825 92
453 0,326 635 7 0,043 766 00 1,758 943 8 0,153 40 0,020 55 0,826 05
454 0,322 886 8 0,045 842 67 1,752 466 3 0,152 22 0,021 61 0,826 17
455 0,318 700 0 0,048 000 00 1,744 100 0 0,150 99 0,022 74 0,826 27
456 0,314 025 1 0,050 243 68 1,733 559 5 0,149 69 0,023 95 0,826 36
457 0,308 884 0 0,052 573 04 1,720 858 1 0,148 34 0,025 25 0,826 41
458 0,303 290 4 0,054 980 56 1,705 936
...
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