Paper and board — Determination of colour by diffuse reflectance — Part 1: Indoor daylight conditions (C/2 degrees)

ISO 5631-1:2015 specifies a method for measuring the colour of paper and board by the diffuse reflectance method with the elimination of specular gloss. ISO 5631-1:2015 is not applicable to coloured papers or boards which incorporate fluorescent dyes or pigments. It may be used to determine the colour of papers or boards which contain fluorescent whitening agents provided the UV content of the illumination on the test piece has been adjusted to conform to that in the CIE illuminant C, using a fluorescent reference standard that fulfils the requirements for international fluorescent reference standards of level 3 (IR3) as prescribed by ISO 2469 with an assigned ISO brightness value (C/2°) provided by an authorized laboratory, as described in ISO 2470‑1.

Papier et carton — Détermination de la couleur par réflectance diffuse — Partie 1: Conditions d'éclairage intérieur de jour (C/2 degrés)

ISO 5631-1:2015 spécifie une méthode pour mesurer la couleur du papier et du carton par la méthode de la réflectance diffuse avec élimination du brillant spéculaire. ISO 5631-1:2015 n'est pas applicable aux papiers et cartons colorés qui contiennent des colorants ou des pigments fluorescents. Elle peut être utilisée pour déterminer la couleur des papiers et cartons contenant des agents d'azurage fluorescents, sous réserve que la teneur en UV de l'éclairage sur l'éprouvette ait été ajustée de manière à être conforme à celle de l'illuminant CIE C, à l'aide d'un étalon de référence fluorescent satisfaisant aux exigences applicables aux étalons de référence fluorescents internationaux de niveau 3 (IR3), comme prescrit dans l'ISO 2469, présentant un degré de blancheur ISO (C/2°) dont la valeur a été attribuée par un laboratoire agréé, comme décrit dans l'ISO 2470‑1.

Papir, karton in lepenka - Določanje barve z razpršeno odsevnostjo - 1. del: Pogoji osvetlitve v prostoru (C/2°)

Ta del standarda ISO 5631 opredeljuje metodo merjenja barve papirja, kartona in lepenke z metodo razpršene odsevnosti z odstranitvijo refleksijskega sijaja.
Ta del standarda ISO 5631 se ne uporablja za barvni papir ali karton oz. lepenko, ki vsebuje fluorescentne barve ali pigmente. Uporablja se lahko za določanje barve papirja ali kartona oz. lepenke, ki vsebuje fluorescentna belilna sredstva, pod pogojem, da je bila vsebnost UV-osvetlitve testnega primerka prilagojena tako, da ustreza vrsti svetlobe CIE C, pri čemer je treba uporabiti referenčni standard za fluorescenco, ki izpolnjuje zahteve mednarodnih referenčnih standardov za fluorescenco 3. ravni (IR3), kot zahteva standard ISO 2469, z dodeljeno vrednostjo svetlosti ISO (C/2°), ki jo je določil pooblaščeni laboratorij, kot je opisano v standardu ISO 2470-1.

General Information

Status
Withdrawn
Publication Date
25-Oct-2015
Current Stage
9599 - Withdrawal of International Standard
Completion Date
19-Jul-2022

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INTERNATIONAL ISO
STANDARD 5631-1
Second edition
2015-11-01
Paper and board — Determination of
colour by diffuse reflectance —
Part 1:
Indoor daylight conditions
(C/2°)
Papier et carton — Détermination de la couleur par réflectance
diffuse —
Partie 1: Conditions d’éclairage intérieur de jour (C/2°)
Reference number
ISO 5631-1:2015(E)
ISO 2015
---------------------- Page: 1 ----------------------
ISO 5631-1:2015(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, 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 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.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2015 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 5631-1:2015(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 3

5 Apparatus ..................................................................................................................................................................................................................... 3

5.1 Reflectometer ........................................................................................................................................................................................... 3

6 Sampling and conditioning ........................................................................................................................................................................ 4

7 Preparation of test pieces ........................................................................................................................................................................... 4

8 Procedure..................................................................................................................................................................................................................... 4

9 Calculation .................................................................................................................................................................................................................. 4

9.1 CIE tristimulus values ....................................................................................................................................................................... 4

9.2 CIELAB coordinates ............................................................................................................................................................................ 5

9.3 Dispersion of the results ................................................................................................................................................................. 5

10 Expression of results ........................................................................................................................................................................................ 6

11 Precision ....................................................................................................................................................................................................................... 6

12 Test report ................................................................................................................................................................................................................... 6

Annex A (normative) Spectral characteristics of reflectometers for determining

tristimulus values ................................................................................................................................................................................................ 7

Bibliography .............................................................................................................................................................................................................................13

© ISO 2015 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 5631-1:2015(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 on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical

Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information

The committee responsible for this document is ISO/TC 6, Paper, board and pulps.

This second edition cancels and replaces the first edition (ISO 5631-1:2009). The major change is to

allow for calculations using ASTM E308 for instruments that have bandpass correction and still

maintain the procedure for instruments without bandpass correction.

ISO 5631 consists of the following parts, under the general title Paper and board — Determination of

colour by diffuse reflectance:
— Part 1: Indoor daylight conditions (C/2°)
— Part 2: Outdoor daylight conditions (D65/10°)
— Part 3: Indoor illumination conditions (D50/2°)
iv © ISO 2015 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 5631-1:2015(E)
Introduction

The colour of an object can be uniquely characterized by means of a triplet of colour coordinates such

as the CIE tristimulus values or the CIELAB 1976 L*, a*, b* coordinates for a specified CIE illuminant and

CIE standard observer.

Apart from the optical properties of the sample, the values of such coordinates depend upon the

conditions of measurement, particularly the spectral and geometric characteristics of the instrument

used. This part of ISO 5631 should therefore be read in conjunction with ISO 2469.

This part of ISO 5631 describes the measurement and description of colour in terms of the CIE

illuminant C and the CIE 1931 (2°) standard observer. The other parts of this International Standard

describe measurements and calculations carried out in an analogous manner using either the CIE

standard illuminant D65 and the CIE 1964 (10°) standard observer or the CIE illuminant D50 and the

CIE 1931 (2°) standard observer.

The choice of illuminant conditions is important when determining the colour coordinates of white

papers containing a fluorescent whitening agent. In ISO 5631-2, the UV content of the illumination is

much higher, approximating UV levels encountered in outdoor viewing conditions.

ISO 5631-3 describes the measurement and description of colour in terms of the CIE illuminant D50

and the CIE 1931 (2°) standard observer. This method is especially applicable to graphic arts situations

since these illuminant/observer conditions are used within the graphic arts industry.

© ISO 2015 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 5631-1:2015(E)
Paper and board — Determination of colour by diffuse
reflectance —
Part 1:
Indoor daylight conditions (C/2°)
1 Scope

This part of ISO 5631 specifies a method for measuring the colour of paper and board by the diffuse

reflectance method with the elimination of specular gloss.

This part of ISO 5631 is not applicable to coloured papers or boards which incorporate fluorescent dyes

or pigments. It may be used to determine the colour of papers or boards which contain fluorescent

whitening agents provided the UV content of the illumination on the test piece has been adjusted

to conform to that in the CIE illuminant C, using a fluorescent reference standard that fulfils the

requirements for international fluorescent reference standards of level 3 (IR3) as prescribed by

ISO 2469 with an assigned ISO brightness value (C/2°) provided by an authorized laboratory, as

described in ISO 2470-1.
2 Normative references

The following referenced documents are indispensable for the application 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 186, Paper and board — Sampling to determine average quality

ISO 2469, Paper, board and pulps — Measurement of diffuse radiance factor (diffuse reflectance factor)

ISO 2470-1, Paper, board and pulps — Measurement of diffuse blue reflectance factor — Part 1: Indoor

daylight conditions (ISO brightness)

ASTM E308, Standard Practice for Computing the Colors of Objects by Using the CIE System

CIE Publication 15:2004, Colorimetry, 3rd ed
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
radiance factor

ratio of the radiance of a surface element of a body in the direction delimited by a given cone, with its apex

at the surface element, to that of the perfect reflecting diffuser under the same conditions of illumination

Note 1 to entry: For fluorescent (luminescent) materials, the total radiance factor, β, is the sum of two portions,

the reflected radiance factor, β , and the luminescent radiance factor, β , so that β = β + β .

R L R L

For non-fluorescent materials, the reflected radiance factor, β , is numerically equal to the reflectance factor, R.

© ISO 2015 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 5631-1:2015(E)
3.2
intrinsic radiance factor

radiance factor of a layer or pad of material thick enough to be opaque, such that increasing the thickness

of the pad by doubling the number of sheets results in no change in the measured radiance factor

Note 1 to entry: The intrinsic radiance factor is often expressed as a percentage.

3.3
reflectance factor

ratio of the radiation reflected by a surface element of a body in the direction delimited by a given cone,

with its apex at the surface element to that of the perfect reflecting diffuser under the same conditions

of illumination
Note 1 to entry: The ratio is often expressed as a percentage.

Note 2 to entry: The reflectance factor is influenced by the backing if the body is translucent.

3.4
intrinsic reflectance factor

reflectance factor of a layer or pad of material thick enough to be opaque, such that increasing the thickness

of the pad by doubling the number of sheets results in no change in the measured reflectance factor

Note 1 to entry: The reflectance factor of a non-opaque sheet is dependent on the background and is not a

material property.
3.5
tristimulus values
X, Y, Z

amount of the three reference colour stimuli, in a given chromatic system, required to match the

stimulus considered

Note 1 to entry: In this part of ISO 5631, the CIE illuminant C and the CIE 1931 (2°) standard observer are used to

define the trichromatic system.

Note 2 to entry: No subscript is applied to conform to the CIE convention that tristimulus values have no subscript

when the CIE 1931 (2°) standard observer is used [the subscript 10 is applied for tristimulus values that are

obtained using the CIE 1964 (10°) standard observer].
3.6
CIELAB colour space

three-dimensional, approximately uniform colour space, produced by plotting, in rectangular

coordinates L*, a*, b*, quantities defined by the formulae given in Clause 9

Note 1 to entry: The quantity, L*, is a measure of the lightness of the test piece, where L* = 0 corresponds to black

and L* = 100 is defined by the perfect reflecting diffuser. Visually, the quantities a* and b* represent respectively

the red-green and yellow-blue axes in colour space, such that
+a* is a measure of the degree of redness of the test piece,
−a* is a measure of the degree of greenness of the test piece,
+b* is a measure of the degree of yellowness of the test piece, and
−b* is a measure of the degree of blueness of the test piece.
If both a* and b* are equal to zero, the test piece is achromatic.
2 © ISO 2015 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 5631-1:2015(E)
4 Principle

The light reflected from a sample under specified conditions is analysed either by a tristimulus-filter

colourimeter or by an abridged spectrophotometer, and the colour coordinates are then calculated for

C/2° conditions.
5 Apparatus
5.1 Reflectometer

5.1.1 Reflectometer, having the geometric, spectral and photometric characteristics described in

ISO 2469, and calibrated in accordance with the provisions of ISO 2469.

If materials containing fluorescent whitening agents are to be measured, the reflectometer shall be

equipped with a radiation source having an adequate UV content control, adjusted to a UV condition

corresponding to the C illuminant by the use of a reference standard, as described in ISO 2470-1.

5.1.2 In the case of a filter reflectometer, a set of filters that, in conjunction with the optical

characteristics of the basic instrument, give overall responses equivalent to the CIE tristimulus values X,

Y and Z of the CIE 1931 standard colourimetric system of the test piece evaluated for the CIE illuminant C.

In the case of a filter reflectometer, the radiation falling upon the test piece shall have a UV content

corresponding to that of the CIE illuminant C.

5.1.3 In the case of an abridged spectrophotometer, a function that permits calculation of the CIE

tristimulus values X, Y and Z of the CIE 1931 standard colourimetric system of the test piece evaluated

for the CIE illuminant C using the weighting functions given in Annex A where the Tables A.1 and A.2 are

used for instruments without bandpass correction and Tables A.3 and A.4 are used for instruments with

bandpass correction.

In the case of an abridged spectrophotometer, the instrument shall have an adjustable filter with a

cut-off wavelength of 395 nm or some other equivalent system, and this filter shall be adjusted or the

system shall be calibrated with the help of the fluorescent reference standard (5.2.2), so that the UV

content of the illumination falling upon the sample corresponds to that of the CIE illuminant C.

5.2 Reference standards, for calibration of the instrument and the working standards and used

frequently enough to ensure satisfactory calibration and UV adjustment.

5.2.1 Non-fluorescent reference standard, for photometric calibration, issued by an authorized

laboratory in accordance with the provisions of ISO 2469.

5.2.2 Fluorescent reference standard, for use in adjusting the UV content of the radiation incident

upon the sample, having an ISO brightness valu
...

SLOVENSKI STANDARD
oSIST ISO 5631-1:2016
01-maj-2016

3DSLUNDUWRQLQOHSHQND'RORþDQMHEDUYH]UD]SUãHQRRGVHYQRVWMRGHO3RJRML

RVYHWOLWYHYSURVWRUX &ƒ

Paper and board - Determination of colour by diffuse reflectance - Part 1: Indoor daylight

conditions (C/2 degrees)

Papier et carton -- Détermination de la couleur par réflectance diffuse -- Partie 1:

Conditions d'éclairage intérieur de jour (C/2 degrés)
Ta slovenski standard je istoveten z: ISO 5631-1:2015
ICS:
85.060 Papir, karton in lepenka Paper and board
oSIST ISO 5631-1:2016 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST ISO 5631-1:2016
---------------------- Page: 2 ----------------------
oSIST ISO 5631-1:2016
INTERNATIONAL ISO
STANDARD 5631-1
Second edition
2015-11-01
Paper and board — Determination of
colour by diffuse reflectance —
Part 1:
Indoor daylight conditions
(C/2 °)
Papier et carton — Détermination de la couleur par réflectance
diffuse —
Partie 1: Conditions d’éclairage intérieur de jour (C/2 °)
Reference number
ISO 5631-1:2015(E)
ISO 2015
---------------------- Page: 3 ----------------------
oSIST ISO 5631-1:2016
ISO 5631-1:2015(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, 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 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.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2015 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST ISO 5631-1:2016
ISO 5631-1:2015(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 3

5 Apparatus ..................................................................................................................................................................................................................... 3

5.1 Reflectometer ........................................................................................................................................................................................... 3

6 Sampling and conditioning ........................................................................................................................................................................ 4

7 Preparation of test pieces ........................................................................................................................................................................... 4

8 Procedure..................................................................................................................................................................................................................... 4

9 Calculation .................................................................................................................................................................................................................. 4

9.1 CIE tristimulus values ....................................................................................................................................................................... 4

9.2 CIELAB coordinates ............................................................................................................................................................................ 5

9.3 Dispersion of the results ................................................................................................................................................................. 5

10 Expression of results ........................................................................................................................................................................................ 6

11 Precision ....................................................................................................................................................................................................................... 6

12 Test report ................................................................................................................................................................................................................... 6

Annex A (normative) Spectral characteristics of reflectometers for determining

tristimulus values ................................................................................................................................................................................................ 7

Bibliography .............................................................................................................................................................................................................................13

© ISO 2015 – All rights reserved iii
---------------------- Page: 5 ----------------------
oSIST ISO 5631-1:2016
ISO 5631-1:2015(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 on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical

Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information

The committee responsible for this document is ISO/TC 6, Paper, board and pulps.

This second edition cancels and replaces the first edition (ISO 5631-1:2009). The major change is to

allow for calculations using ASTM E308 for instruments that have bandpass correction and still

maintain the procedure for instruments without bandpass correction.

ISO 5631 consists of the following parts, under the general title Paper and board — Determination of

colour by diffuse reflectance:
— Part 1: Indoor daylight conditions (C/2°)
— Part 2: Outdoor daylight conditions (D65/10°)
— Part 3: Indoor illumination conditions (D50/2°)
iv © ISO 2015 – All rights reserved
---------------------- Page: 6 ----------------------
oSIST ISO 5631-1:2016
ISO 5631-1:2015(E)
Introduction

The colour of an object can be uniquely characterized by means of a triplet of colour coordinates such

as the CIE tristimulus values or the CIELAB 1976 L*, a*, b* coordinates for a specified CIE illuminant and

CIE standard observer.

Apart from the optical properties of the sample, the values of such coordinates depend upon the

conditions of measurement, particularly the spectral and geometric characteristics of the instrument

used. This part of ISO 5631 should therefore be read in conjunction with ISO 2469.

This part of ISO 5631 describes the measurement and description of colour in terms of the CIE

illuminant C and the CIE 1931 (2°) standard observer. The other parts of this International Standard

describe measurements and calculations carried out in an analogous manner using either the CIE

standard illuminant D65 and the CIE 1964 (10°) standard observer or the CIE illuminant D50 and the

CIE 1931 (2°) standard observer.

The choice of illuminant conditions is important when determining the colour coordinates of white

papers containing a fluorescent whitening agent. In ISO 5631-2, the UV content of the illumination is

much higher, approximating UV levels encountered in outdoor viewing conditions.

ISO 5631-3 describes the measurement and description of colour in terms of the CIE illuminant D50

and the CIE 1931 (2°) standard observer. This method is especially applicable to graphic arts situations

since these illuminant/observer conditions are used within the graphic arts industry.

© ISO 2015 – All rights reserved v
---------------------- Page: 7 ----------------------
oSIST ISO 5631-1:2016
---------------------- Page: 8 ----------------------
oSIST ISO 5631-1:2016
INTERNATIONAL STANDARD ISO 5631-1:2015(E)
Paper and board — Determination of colour by diffuse
reflectance —
Part 1:
Indoor daylight conditions (C/2 °)
1 Scope

This part of ISO 5631 specifies a method for measuring the colour of paper and board by the diffuse

reflectance method with the elimination of specular gloss.

This part of ISO 5631 is not applicable to coloured papers or boards which incorporate fluorescent dyes

or pigments. It may be used to determine the colour of papers or boards which contain fluorescent

whitening agents provided the UV content of the illumination on the test piece has been adjusted

to conform to that in the CIE illuminant C, using a fluorescent reference standard that fulfils the

requirements for international fluorescent reference standards of level 3 (IR3) as prescribed by

ISO 2469 with an assigned ISO brightness value (C/2°) provided by an authorized laboratory, as

described in ISO 2470-1.
2 Normative references

The following referenced documents are indispensable for the application 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 186, Paper and board — Sampling to determine average quality

ISO 2469, Paper, board and pulps — Measurement of diffuse radiance factor (diffuse reflectance factor)

ISO 2470-1, Paper, board and pulps — Measurement of diffuse blue reflectance factor — Part 1: Indoor

daylight conditions (ISO brightness)

ASTM E308, Standard Practice for Computing the Colors of Objects by Using the CIE System

CIE Publication 15:2004, Colorimetry, 3rd ed
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
radiance factor

ratio of the radiance of a surface element of a body in the direction delimited by a given cone, with its apex

at the surface element, to that of the perfect reflecting diffuser under the same conditions of illumination

Note 1 to entry: For fluorescent (luminescent) materials, the total radiance factor, β, is the sum of two portions,

the reflected radiance factor, β , and the luminescent radiance factor, β , so that β = β + β .

R L R L

For non-fluorescent materials, the reflected radiance factor, β , is numerically equal to the reflectance factor, R.

© ISO 2015 – All rights reserved 1
---------------------- Page: 9 ----------------------
oSIST ISO 5631-1:2016
ISO 5631-1:2015(E)
3.2
intrinsic radiance factor

radiance factor of a layer or pad of material thick enough to be opaque, such that increasing the thickness

of the pad by doubling the number of sheets results in no change in the measured radiance factor

Note 1 to entry: The intrinsic radiance factor is often expressed as a percentage.

3.3
reflectance factor

ratio of the radiation reflected by a surface element of a body in the direction delimited by a given cone,

with its apex at the surface element to that of the perfect reflecting diffuser under the same conditions

of illumination
Note 1 to entry: The ratio is often expressed as a percentage.

Note 2 to entry: The reflectance factor is influenced by the backing if the body is translucent.

3.4
intrinsic reflectance factor

reflectance factor of a layer or pad of material thick enough to be opaque, such that increasing the thickness

of the pad by doubling the number of sheets results in no change in the measured reflectance factor

Note 1 to entry: The reflectance factor of a non-opaque sheet is dependent on the background and is not a

material property.
3.5
tristimulus values
X, Y, Z

amount of the three reference colour stimuli, in a given chromatic system, required to match the

stimulus considered

Note 1 to entry: In this part of ISO 5631, the CIE illuminant C and the CIE 1931 (2°) standard observer are used to

define the trichromatic system.

Note 2 to entry: No subscript is applied to conform to the CIE convention that tristimulus values have no subscript

when the CIE 1931 (2°) standard observer is used [the subscript 10 is applied for tristimulus values that are

obtained using the CIE 1964 (10°) standard observer].
3.6
CIELAB colour space

three-dimensional, approximately uniform colour space, produced by plotting, in rectangular

coordinates L*, a*, b*, quantities defined by the formulae given in Clause 9

Note 1 to entry: The quantity, L*, is a measure of the lightness of the test piece, where L* = 0 corresponds to black

and L* = 100 is defined by the perfect reflecting diffuser. Visually, the quantities a* and b* represent respectively

the red-green and yellow-blue axes in colour space, such that
+a* is a measure of the degree of redness of the test piece,
−a* is a measure of the degree of greenness of the test piece,
+b* is a measure of the degree of yellowness of the test piece, and
−b* is a measure of the degree of blueness of the test piece.
If both a* and b* are equal to zero, the test piece is achromatic.
2 © ISO 2015 – All rights reserved
---------------------- Page: 10 ----------------------
oSIST ISO 5631-1:2016
ISO 5631-1:2015(E)
4 Principle

The light reflected from a sample under specified conditions is analysed either by a tristimulus-filter

colourimeter or by an abridged spectrophotometer, and the colour coordinates are then calculated for

C/2° conditions.
5 Apparatus
5.1 Reflectometer

5.1.1 Reflectometer, having the geometric, spectral and photometric characteristics described in

ISO 2469, and calibrated in accordance with the provisions of ISO 2469.

If materials containing fluorescent whitening agents are to be measured, the reflectometer shall be

equipped with a radiation source having an adequate UV content control, adjusted to a UV condition

corresponding to the C illuminant by the use of a reference standard, as described in ISO 2470-1.

5.1.2 In the case of a filter reflectometer, a set of filters that, in conjunction with the optical

characteristics of the basic instrument, give overall responses equivalent to the CIE tristimulus values X,

Y and Z of the CIE 1931 standard colourimetric system of the test piece evaluated for the CIE illuminant C.

In the case of a filter reflectometer, the radiation falling upon the test piece shall have a UV content

corresponding to that of the CIE illuminant C.

5.1.3 In the case of an abridged spectrophotometer, a function that permits calculation of the CIE

tristimulus values X, Y and Z of the CIE 1931 standard colourimetric system of the test piece evaluated

for the CIE illuminant C using the weighting functions given in Annex A where the Tables A.1 and A.2 are

used for instruments without bandpass correction and Tables A.3 and A.4 are used for instruments with

bandpass correction.

In the case of an abridged spectrophotometer, the instrument shall have an adjustable filter with a

cut-off wavelength of 395 nm or some other equivalent system, and this filter shall be adjusted or the

system shall be calibrated with the help of the fluorescent reference standard (5.2.2), so that the UV

content of the illumination falling upon the sample corresponds to that o
...

SLOVENSKI STANDARD
SIST ISO 5631-1:2016
01-junij-2016
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SIST ISO 5631-1:2011

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RVYHWOLWYHYSURVWRUX &ƒ

Paper and board - Determination of colour by diffuse reflectance - Part 1: Indoor daylight

conditions (C/2 degrees)

Papier et carton -- Détermination de la couleur par réflectance diffuse -- Partie 1:

Conditions d'éclairage intérieur de jour (C/2 degrés)
Ta slovenski standard je istoveten z: ISO 5631-1:2015
ICS:
85.060 Papir, karton in lepenka Paper and board
SIST ISO 5631-1:2016 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST ISO 5631-1:2016
---------------------- Page: 2 ----------------------
SIST ISO 5631-1:2016
INTERNATIONAL ISO
STANDARD 5631-1
Second edition
2015-11-01
Paper and board — Determination of
colour by diffuse reflectance —
Part 1:
Indoor daylight conditions
(C/2°)
Papier et carton — Détermination de la couleur par réflectance
diffuse —
Partie 1: Conditions d’éclairage intérieur de jour (C/2°)
Reference number
ISO 5631-1:2015(E)
ISO 2015
---------------------- Page: 3 ----------------------
SIST ISO 5631-1:2016
ISO 5631-1:2015(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, 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 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.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2015 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 5631-1:2016
ISO 5631-1:2015(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 3

5 Apparatus ..................................................................................................................................................................................................................... 3

5.1 Reflectometer ........................................................................................................................................................................................... 3

6 Sampling and conditioning ........................................................................................................................................................................ 4

7 Preparation of test pieces ........................................................................................................................................................................... 4

8 Procedure..................................................................................................................................................................................................................... 4

9 Calculation .................................................................................................................................................................................................................. 4

9.1 CIE tristimulus values ....................................................................................................................................................................... 4

9.2 CIELAB coordinates ............................................................................................................................................................................ 5

9.3 Dispersion of the results ................................................................................................................................................................. 5

10 Expression of results ........................................................................................................................................................................................ 6

11 Precision ....................................................................................................................................................................................................................... 6

12 Test report ................................................................................................................................................................................................................... 6

Annex A (normative) Spectral characteristics of reflectometers for determining

tristimulus values ................................................................................................................................................................................................ 7

Bibliography .............................................................................................................................................................................................................................13

© ISO 2015 – All rights reserved iii
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SIST ISO 5631-1:2016
ISO 5631-1:2015(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 on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical

Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information

The committee responsible for this document is ISO/TC 6, Paper, board and pulps.

This second edition cancels and replaces the first edition (ISO 5631-1:2009). The major change is to

allow for calculations using ASTM E308 for instruments that have bandpass correction and still

maintain the procedure for instruments without bandpass correction.

ISO 5631 consists of the following parts, under the general title Paper and board — Determination of

colour by diffuse reflectance:
— Part 1: Indoor daylight conditions (C/2°)
— Part 2: Outdoor daylight conditions (D65/10°)
— Part 3: Indoor illumination conditions (D50/2°)
iv © ISO 2015 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 5631-1:2016
ISO 5631-1:2015(E)
Introduction

The colour of an object can be uniquely characterized by means of a triplet of colour coordinates such

as the CIE tristimulus values or the CIELAB 1976 L*, a*, b* coordinates for a specified CIE illuminant and

CIE standard observer.

Apart from the optical properties of the sample, the values of such coordinates depend upon the

conditions of measurement, particularly the spectral and geometric characteristics of the instrument

used. This part of ISO 5631 should therefore be read in conjunction with ISO 2469.

This part of ISO 5631 describes the measurement and description of colour in terms of the CIE

illuminant C and the CIE 1931 (2°) standard observer. The other parts of this International Standard

describe measurements and calculations carried out in an analogous manner using either the CIE

standard illuminant D65 and the CIE 1964 (10°) standard observer or the CIE illuminant D50 and the

CIE 1931 (2°) standard observer.

The choice of illuminant conditions is important when determining the colour coordinates of white

papers containing a fluorescent whitening agent. In ISO 5631-2, the UV content of the illumination is

much higher, approximating UV levels encountered in outdoor viewing conditions.

ISO 5631-3 describes the measurement and description of colour in terms of the CIE illuminant D50

and the CIE 1931 (2°) standard observer. This method is especially applicable to graphic arts situations

since these illuminant/observer conditions are used within the graphic arts industry.

© ISO 2015 – All rights reserved v
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SIST ISO 5631-1:2016
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SIST ISO 5631-1:2016
INTERNATIONAL STANDARD ISO 5631-1:2015(E)
Paper and board — Determination of colour by diffuse
reflectance —
Part 1:
Indoor daylight conditions (C/2°)
1 Scope

This part of ISO 5631 specifies a method for measuring the colour of paper and board by the diffuse

reflectance method with the elimination of specular gloss.

This part of ISO 5631 is not applicable to coloured papers or boards which incorporate fluorescent dyes

or pigments. It may be used to determine the colour of papers or boards which contain fluorescent

whitening agents provided the UV content of the illumination on the test piece has been adjusted

to conform to that in the CIE illuminant C, using a fluorescent reference standard that fulfils the

requirements for international fluorescent reference standards of level 3 (IR3) as prescribed by

ISO 2469 with an assigned ISO brightness value (C/2°) provided by an authorized laboratory, as

described in ISO 2470-1.
2 Normative references

The following referenced documents are indispensable for the application 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 186, Paper and board — Sampling to determine average quality

ISO 2469, Paper, board and pulps — Measurement of diffuse radiance factor (diffuse reflectance factor)

ISO 2470-1, Paper, board and pulps — Measurement of diffuse blue reflectance factor — Part 1: Indoor

daylight conditions (ISO brightness)

ASTM E308, Standard Practice for Computing the Colors of Objects by Using the CIE System

CIE Publication 15:2004, Colorimetry, 3rd ed
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
radiance factor

ratio of the radiance of a surface element of a body in the direction delimited by a given cone, with its apex

at the surface element, to that of the perfect reflecting diffuser under the same conditions of illumination

Note 1 to entry: For fluorescent (luminescent) materials, the total radiance factor, β, is the sum of two portions,

the reflected radiance factor, β , and the luminescent radiance factor, β , so that β = β + β .

R L R L

For non-fluorescent materials, the reflected radiance factor, β , is numerically equal to the reflectance factor, R.

© ISO 2015 – All rights reserved 1
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SIST ISO 5631-1:2016
ISO 5631-1:2015(E)
3.2
intrinsic radiance factor

radiance factor of a layer or pad of material thick enough to be opaque, such that increasing the thickness

of the pad by doubling the number of sheets results in no change in the measured radiance factor

Note 1 to entry: The intrinsic radiance factor is often expressed as a percentage.

3.3
reflectance factor

ratio of the radiation reflected by a surface element of a body in the direction delimited by a given cone,

with its apex at the surface element to that of the perfect reflecting diffuser under the same conditions

of illumination
Note 1 to entry: The ratio is often expressed as a percentage.

Note 2 to entry: The reflectance factor is influenced by the backing if the body is translucent.

3.4
intrinsic reflectance factor

reflectance factor of a layer or pad of material thick enough to be opaque, such that increasing the thickness

of the pad by doubling the number of sheets results in no change in the measured reflectance factor

Note 1 to entry: The reflectance factor of a non-opaque sheet is dependent on the background and is not a

material property.
3.5
tristimulus values
X, Y, Z

amount of the three reference colour stimuli, in a given chromatic system, required to match the

stimulus considered

Note 1 to entry: In this part of ISO 5631, the CIE illuminant C and the CIE 1931 (2°) standard observer are used to

define the trichromatic system.

Note 2 to entry: No subscript is applied to conform to the CIE convention that tristimulus values have no subscript

when the CIE 1931 (2°) standard observer is used [the subscript 10 is applied for tristimulus values that are

obtained using the CIE 1964 (10°) standard observer].
3.6
CIELAB colour space

three-dimensional, approximately uniform colour space, produced by plotting, in rectangular

coordinates L*, a*, b*, quantities defined by the formulae given in Clause 9

Note 1 to entry: The quantity, L*, is a measure of the lightness of the test piece, where L* = 0 corresponds to black

and L* = 100 is defined by the perfect reflecting diffuser. Visually, the quantities a* and b* represent respectively

the red-green and yellow-blue axes in colour space, such that
+a* is a measure of the degree of redness of the test piece,
−a* is a measure of the degree of greenness of the test piece,
+b* is a measure of the degree of yellowness of the test piece, and
−b* is a measure of the degree of blueness of the test piece.
If both a* and b* are equal to zero, the test piece is achromatic.
2 © ISO 2015 – All rights reserved
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SIST ISO 5631-1:2016
ISO 5631-1:2015(E)
4 Principle

The light reflected from a sample under specified conditions is analysed either by a tristimulus-filter

colourimeter or by an abridged spectrophotometer, and the colour coordinates are then calculated for

C/2° conditions.
5 Apparatus
5.1 Reflectometer

5.1.1 Reflectometer, having the geometric, spectral and photometric characteristics described in

ISO 2469, and calibrated in accordance with the provisions of ISO 2469.

If materials containing fluorescent whitening agents are to be measured, the reflectometer shall be

equipped with a radiation source having an adequate UV content control, adjusted to a UV condition

corresponding to the C illuminant by the use of a reference standard, as described in ISO 2470-1.

5.1.2 In the case of a filter reflectometer, a set of filters that, in conjunction with the optical

characteristics of the basic instrument, give overall responses equivalent to the CIE tristimulus values X,

Y and Z of the CIE 1931 standard colourimetric system of the test piece evaluated for the CIE illuminant C.

In the case of a filter reflectometer, the radiation falling upon the test piece shall have a UV content

corresponding to that of the CIE illuminant C.

5.1.3 In the case of an abridged spectrophotometer, a function that permits calculation of the CIE

tristimulus values X, Y and Z of the CIE 1931 standard colourimetric system of the test piece evaluated

for the CIE illuminant C using the weighting functions given in Annex A where the Tables A.1 and A.2 are

used for instruments without bandpass correction and Tables A.3 and A.4 are used for instruments with

bandpass correction.

In the case of an abridged spectrophotometer, the instrument shall have an adjustable filter with a

cut-off wavelength of 395 nm or some other equivalent system, and this filter shall be adjusted or the

system shall be calibrated with the help of the fluorescent reference standard (5.2.2), so that the UV

content of the illumination falling upon the sample corres
...

NORME ISO
INTERNATIONALE 5631-1
Deuxième édition
2015-11-01
Papier et carton — Détermination de
la couleur par réflectance diffuse —
Partie 1:
Conditions d’éclairage intérieur
de jour (C/2°)
Paper and board — Determination of colour by diffuse reflectance
—Part 1: Indoor daylight conditions (C/2°)
Numéro de référence
ISO 5631-1:2015(F)
ISO 2015
---------------------- Page: 1 ----------------------
ISO 5631-1:2015(F)
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2015, Publié en Suisse

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni utilisée

sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie, l’affichage sur

l’internet ou sur un Intranet, sans autorisation écrite préalable. Les demandes d’autorisation peuvent être adressées à l’ISO à

l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2015 – Tous droits réservés
---------------------- Page: 2 ----------------------
ISO 5631-1:2015(F)
Sommaire Page

Avant-propos ..............................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Domaine d’application ................................................................................................................................................................................... 1

2 Références normatives ................................................................................................................................................................................... 1

3 Termes et définitions ....................................................................................................................................................................................... 1

4 Principe .......................................................................................................................................................................................................................... 3

5 Appareillage .............................................................................................................................................................................................................. 3

6 Échantillonnage et conditionnement .............................................................................................................................................. 4

7 Préparation des éprouvettes ................................................................................................................................................................... 4

8 Mode opératoire.................................................................................................................................................................................................... 4

9 Calcul ................................................................................................................................................................................................................................ 5

9.1 Composantes trichromatiques CIE ........................................................................................................................................ 5

9.2 Coordonnées CIELAB ......... ................................................................................................................................................................ 5

9.3 Dispersion des résultats ................................................................................................................................................................. 5

10 Expression des résultats............................................................................................................................................................................... 6

11 Fidélité ............................................................................................................................................................................................................................ 6

12 Rapport d’essai ....................................................................................................................................................................................................... 6

Annexe A (normative) Caractéristiques spectrales des réflectomètres pour déterminer les

composantes trichromatiques ............................................................................................................................................................... 7

Bibliographie ...........................................................................................................................................................................................................................13

© ISO 2015 – Tous droits réservés iii
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ISO 5631-1:2015(F)
Avant-propos

L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes

nationaux de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est

en général confiée aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude

a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,

gouvernementales et non gouvernementales, en liaison avec l’ISO participent également aux travaux.

L’ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui

concerne la normalisation électrotechnique.

Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont

décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents

critères d’approbation requis pour les différents types de documents ISO. Le présent document a été

rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www.

iso.org/directives).

L’attention est appelée sur le fait que certains des éléments du présent document peuvent faire l’objet de

droits de propriété intellectuelle ou de droits analogues. L’ISO ne saurait être tenue pour responsable

de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant

les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de

l’élaboration du document sont indiqués dans l’Introduction et/ou dans la liste des déclarations de

brevets reçues par l’ISO (voir www.iso.org/brevets).

Les appellations commerciales éventuellement mentionnées dans le présent document sont données

pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer

un engagement.

Pour une explication de la signification des termes et expressions spécifiques de l’ISO liés à

l’évaluation de la conformité, ou pour toute information au sujet de l’adhésion de l’ISO aux principes

de l’OMC concernant les obstacles techniques au commerce (OTC), voir le lien suivant: Avant-propos —

Informations supplémentaires.

Le comité chargé de l’élaboration du présent document est l’ISO/TC 6, Papiers, cartons et pâtes.

Cette deuxième édition annule et remplace la première édition (ISO 5631-1:2009). La principale

modification apportée vise à permettre d’effectuer les calculs à l’aide de l’ASTM E308 pour les appareils

qui intègrent une correction de la bande passante, tout conservant le même mode opératoire pour les

appareils sans correction de la bande passante.

L’ISO 5631 comprend les parties suivantes, présentées sous le titre général Papier et carton —

Détermination de la couleur par réflectance diffuse:
— Partie 1: Conditions d’éclairage intérieur de jour (C/2°)
— Partie 2: Conditions de lumière du jour extérieure (D65/10°)
— Partie 3: Conditions d’éclairage intérieur (D50/2°)
iv © ISO 2015 – Tous droits réservés
---------------------- Page: 4 ----------------------
ISO 5631-1:2015(F)
Introduction

La couleur d’un objet peut être caractérisée de manière unique au moyen d’un triplet de coordonnées

colorimétriques telles que les composantes trichromatiques CIE ou les coordonnées L*, a*, b*

CIELAB 1976, pour un illuminant CIE et un observateur normalisé CIE spécifiés.

Outre les propriétés optiques de l’échantillon, les valeurs de ces coordonnées dépendent des conditions

de mesurage, notamment des caractéristiques spectrales et géométriques de l’appareil utilisé. Il

convient donc de lire la présente partie de l’ISO 5631 conjointement avec l’ISO 2469.

La présente partie de l’ISO 5631 détaille le mesurage et la description de la couleur avec l’illuminant

CIE C et l’observateur normalisé CIE 1931 (2°). Les autres parties de la présente Norme internationale

décrivent les mesurages et les calculs effectués de manière analogue en utilisant soit l’illuminant

normalisé CIE D65 et l’observateur normalisé CIE 1964 (10°), soit l’illuminant CIE D50 et l’observateur

normalisé CIE 1931 (2°).

Le choix des conditions relatives à l’illuminant est important lorsqu’il s’agit de déterminer les

coordonnées colorimétriques de papiers blancs contenant un agent d’azurage fluorescent. Dans

l’ISO 5631-2, la teneur en UV de l’éclairage est très supérieure, avoisinant les niveaux d’UV rencontrés

dans des conditions d’observation en extérieur.

L’ISO 5631-3 détaille le mesurage et la description de la couleur avec l’illuminant CIE D50 et l’observateur

normalisé CIE 1931 (2°). Cette méthode convient particulièrement bien au domaine des arts graphiques

car elle correspond aux conditions d’illuminant et d’observateur utilisées dans ce secteur.

© ISO 2015 – Tous droits réservés v
---------------------- Page: 5 ----------------------
NORME INTERNATIONALE ISO 5631-1:2015(F)
Papier et carton — Détermination de la couleur par
réflectance diffuse —
Partie 1:
Conditions d’éclairage intérieur de jour (C/2°)
1 Domaine d’application

La présente partie de l’ISO 5631 spécifie une méthode pour mesurer la couleur du papier et du carton

par la méthode de la réflectance diffuse avec élimination du brillant spéculaire.

La présente partie de l’ISO 5631 n’est pas applicable aux papiers et cartons colorés qui contiennent des

colorants ou des pigments fluorescents. Elle peut être utilisée pour déterminer la couleur des papiers et

cartons contenant des agents d’azurage fluorescents, sous réserve que la teneur en UV de l’éclairage sur

l’éprouvette ait été ajustée de manière à être conforme à celle de l’illuminant CIE C, à l’aide d’un étalon

de référence fluorescent satisfaisant aux exigences applicables aux étalons de référence fluorescents

internationaux de niveau 3 (IR3), comme prescrit dans l’ISO 2469, présentant un degré de blancheur

ISO (C/2°) dont la valeur a été attribuée par un laboratoire agréé, comme décrit dans l’ISO 2470-1.

2 Références normatives

Les documents de référence suivants sont indispensables pour l’application du présent document. Pour

les références datées, seule l’édition citée s’applique. Pour les références non datées, la dernière édition

du document de référence s’applique (y compris les éventuels amendements).
ISO 186, Papier et carton — Échantillonnage pour déterminer la qualité moyenne

ISO 2469, Papier, carton et pâtes — Mesurage du facteur de luminance énergétique diffuse (facteur de

réflectance diffuse)

ISO 2470-1, Papier, carton et pâtes — Mesurage du facteur de réflectance diffuse dans le bleu — Partie 1:

Conditions d’éclairage intérieur de jour (degré de blancheur ISO)

ASTM E308, Standard Practice for Computing the Colors of Objects by Using the CIE System

CIE Publication 15:2004, Colorimetry, 3rd ed.
3 Termes et définitions

Pour les besoins du présent document, les termes et définitions suivants s’appliquent.

3.1
facteur de luminance énergétique

rapport de la luminance énergétique d’un élément de surface d’un corps dans la direction délimitée par

un cône donné dont le sommet se trouve au niveau de l’élément de surface, à la luminance énergétique

du diffuseur parfait par réflexion, dans les mêmes conditions d’éclairage

Note 1 à l’article: Pour les matériaux fluorescents (luminescents), le facteur de luminance énergétique totale, β,

est la somme de deux grandeurs, le facteur de luminance énergétique par réflexion, β , et le facteur de luminance

énergétique par luminescence, β , de sorte que: β = β + β .
L R L
© ISO 2015 – Tous droits réservés 1
---------------------- Page: 6 ----------------------
ISO 5631-1:2015(F)

Pour les matériaux non fluorescents, le facteur de luminance énergétique par réflexion, β , est numériquement

égal au facteur de réflectance, R.
3.2
facteur de luminance énergétique intrinsèque

facteur de luminance énergétique d’une couche ou d’une liasse de matériau suffisamment épaisse

pour être opaque, de sorte que l’augmentation de l’épaisseur de la liasse par doublement du nombre de

feuilles la constituant n’engendre aucune modification du facteur de luminance énergétique mesuré

Note 1 à l’article: Le facteur de luminance énergétique intrinsèque est souvent exprimé sous forme de pourcentage.

3.3
facteur de réflectance

rapport du rayonnement réfléchi par un élément de surface d’un corps dans la direction délimitée par

un cône donné dont le sommet se trouve au niveau de l’élément de surface, au rayonnement réfléchi par

le diffuseur parfait par réflexion, dans les mêmes conditions d’éclairage
Note 1 à l’article: Ce rapport est souvent exprimé sous forme de pourcentage.

Note 2 à l’article: Le fond a une incidence sur le facteur de réflectance si le corps est translucide.

3.4
facteur de réflectance intrinsèque

facteur de réflectance d’une couche ou d’une liasse de matériau suffisamment épaisse pour être

opaque, de sorte que l’augmentation de l’épaisseur de la liasse par doublement du nombre de feuilles la

constituant n’engendre aucune modification du facteur de réflectance mesuré

Note 1 à l’article: Le facteur de réflectance d’une feuille non opaque dépend du fond et n’est pas une propriété du

matériau.
3.5
composantes trichromatiques
X, Y, Z

quantité des trois stimuli de couleur normalisés, dans un système chromatique donné, nécessaire pour

correspondre à la couleur du stimulus considéré

Note 1 à l’article: Dans la présente partie de l’ISO 5631, l’illuminant CIE C et l’observateur normalisé CIE 1931 (2°)

sont utilisés pour définir le système trichromatique.

Note 2 à l’article: Aucun indice n’est utilisé pour respecter la convention CIE selon laquelle les composantes

trichromatiques ne comportent pas d’indice lorsque l’on utilise l’observateur normalisé CIE 1931 (2°) [l’indice 10

est utilisé pour les composantes trichromatiques obtenues lorsque l’on utilise l’observateur normalisé

CIE 1964 (10°)].
3.6
espace chromatique CIELAB

espace chromatique à trois dimensions approximativement uniforme, obtenu en portant en coordonnées

rectangulaires les grandeurs L*, a*, b* définies par les formules données dans l’Article 9

Note 1 à l’article: La grandeur L* est une mesure de la clarté de l’éprouvette, où L* = 0 correspond au noir et

L* = 100 est définie comme étant le diffuseur parfait par réflexion. Visuellement, les grandeurs a* et b*

représentent respectivement les axes rouge-vert et jaune-bleu de l’espace chromatique, de sorte que:

+a* est une mesure de la composante rouge de l’éprouvette;
−a* est une mesure de la composante verte de l’éprouvette;
+b* est une mesure de la composante jaune de l’éprouvette;
−b* est une mesure de la composante bleue de l’éprouvette.
2 © ISO 2015 – Tous droits réservés
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ISO 5631-1:2015(F)
Si a* et b* sont toutes les deux égales à zéro, l’éprouvette est achromatique.
4 Principe

La lumière réfléchie par un échantillon dans des conditions spécifiées est analysée soit au moyen d’un

colorimètre à filtre trichromatique, soit à l’aide d’un spectrophotomètre continu, et les coordonnées

colorimétriques sont calculées pour les conditions C/2°.
5 Appareillage
5.1 Réflectomètre

5.1.1 Réflectomètre, ayant les caractéristiques géométriques, spectrales et photométriques décrites

dans l’ISO 2469 et étalonné conformément aux dispositions de l’ISO 2469.

Si des matériaux contenant des agents d’azurage fluorescents doivent être mesurés, le réflectomètre

doit être équipé d’une source de rayonnement avec un contrôle adéquat de la teneur en UV, réglée à

un niveau correspondant à l’illuminant C au moyen d’un étalon de référence, comme décrit dans

l’ISO 2470-1.

5.1.2 En cas d’utilisation d’un réflectomètre à filtre, un ensemble de filtres qui donne, conjointement

aux caractéristiques optiques de l’appareil de base, des réponses globales équivalentes aux composantes

trichromatiques CIE X, Y et Z du système colorimétrique normalisé CIE 1931 de l’éprouvette évaluée

pour l’illuminant CIE C.

Dans le cas d’un réflectomètre à filtre, le rayonnement tombant sur l’éprouvette doit avoir une teneur

en UV correspondant à celle de l’illuminant CIE C.

5.1.3 En cas d’utilisation d’un spectrophotomètre continu, une fonction permettant de calculer

les composantes trichromatiques CIE X, Y et Z du système colorimétrique normalisé CIE 1931 de

l’éprouvette évaluée pour l’illuminant CIE C, en utilisant les fonctions de pondération indiquées en

Annexe A, les Tableaux A.1 et A.2 étant utilisés pour les appareils sans correction de la bande passante et

les Tableaux A.3 et A.4 pour les appareils avec correction de la bande passante.

Dans le cas d’un spectrophotomètre continu, l’appareil doit être équipé d’un filtre réglable avec une

longueur d’onde de coupure de 395 nm ou d’un système équivalent; ce filtre doit être réglé ou le système

doit être étalonné à l’aide de l’étalon de référence fluorescent (5.2.2), de sorte que la teneur en UV du

rayonnement tombant sur l’échantillon corresponde à celle de l’illuminant CIE C.

5.2 Étalons de référence, pour l’étalonnage de l’appareil et des étalons de travail, utilisés de manière

suffisamment fréquente pour garantir un étalonnage et un réglage du rayonnement UV satisfaisants.

5.2.1 Étalon de référence non fluorescent, pour l’étalonnage photométrique, provenant d’un

laboratoire agréé conformément aux dispositions de l’ISO 2469.

5.2.2 Étalon de référence fluorescent, destiné au réglage de la teneur en UV du rayonnement incident

tombant sur l’échantillon, présentant un degré de blancheur ISO dont la valeur a été attribuée par un

laboratoire agréé, comme prescrit dans l’ISO 2470-1.

5.3 Étalons de travail, étalonnés de manière suffisamment fréquente pour garantir le maintien d’un

étalonnage satisfaisant.

5.3.1 Deux plaques de verre opale, en céramique ou tout autre matériau adapté, nettoy

...

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