ISO 3664:2025

Graphic technology and photography — Viewing conditions

This document specifies viewing conditions for images on both reflective and transmissive media, such as prints (both photographic and photomechanical) and transparencies. This document applies to — critical evaluation of and comparison between transparencies, backlighted signs, reflection photographic or photomechanical prints and/or a reference object or image, — appraisal of the tone reproduction and colourfulness of prints and transparencies at illumination levels similar to those for practical use, including routine inspection, and — critical appraisal of transparencies which are viewed by projection, for comparison with prints, objects, or other reproductions. This document is not applicable to soft-proofing displays, for paper manufacture, and other applications outside of graphic technology and photography.

Technologie graphique et photographie — Conditions d'examen visuel

General Information

• Status: Published
• Publication Date: 10-Jul-2025
• ICS: 37.040.01 - Photography in general
• ICS: 37.100.01 - Graphic technology in general
• Technical Committee: ISO/TC 42 - Photography
• Drafting Committee: ISO/TC 42 - Photography
• Current Stage: 6060 - International Standard published
• Start Date: 11-Jul-2025
• Due Date: 21-Jun-2025
• Completion Date: 11-Jul-2025

Relations

• Revises: ISO 3664:2009 - Graphic technology and photography — Viewing conditions
• Effective Date: 06-Jun-2022

Standards Content (Sample)

International
Standard
ISO 3664
Fourth edition
Graphic technology and
2025-07
photography — Viewing conditions
Technologie graphique et photographie — Conditions
d'examen visuel
Reference number
© ISO 2025
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.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Viewing condition requirements. 5
4.1 General requirements .5
4.1.1 Applicability .5
4.1.2 Ambient conditions .5
4.1.3 Viewing apparatus .6
4.1.4 Spectral conditions for the reference illuminant .6
4.1.5 Maintenance .7
4.2 Conditions for critical comparison (ISO viewing conditions P1, P3, T1) .7
4.2.1 Applicability .7
4.2.2 Illumination .7
4.2.3 Illuminance (P1 and P3) .8
4.2.4 Surround and backing for reflection viewing (P1 and P3) .8
4.2.5 Luminance at the surface of the transparency illuminator (T1) .9
4.2.6 Transparency illuminator diffusion characteristics (T1) .9
4.2.7 Transparency surround (T1) .9
4.2.8 Relationship between transparency luminance and print illuminance (P1 or P3
and T1).9
4.3 Conditions for practical appraisal of prints (including routine inspection) (ISO viewing
condition P2 and P4) .10
4.3.1 Applicability .10
4.3.2 Illumination .10
4.3.3 Illuminance . . .10
4.3.4 Surround and backing .10
4.4 Conditions for viewing small transparencies by projection (ISO viewing conditions T2).11
4.4.1 Applicability .11
4.4.2 Illumination .11
4.4.3 Luminance .11
4.4.4 Uniformity of the projection screen luminance .11
4.4.5 Surround .11
4.4.6 Ambient light and veiling flare .11
4.4.7 Resolution .11
4.4.8 Distortion .11
5 Test methods .12
5.1 Spectral measurements . 12
5.2 Illuminance and luminance . 12
5.3 Resolution assessment for projection viewing apparatus . 12
Annex A (informative) Summary of viewing conditions specified in this document .13
Annex B (informative) Validity of requirements for reference viewing conditions for a print .15
Annex C (informative) Guidelines for judging and exhibiting photographs .18
Annex D (normative) Conformance test to UV content contained in illumination for P3 and P4
condition .20
Annex E (informative) Considerations for simultaneous comparison of samples between
multiple reference viewing environments .24
Bibliography .28

iii
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 Technical Committee ISO/TC 42, Photography, in collaboration with
Technical Committee ISO/TC 130, Graphic technology.
This fourth edition cancels and replaces the third edition (ISO 3664:2009), which has been technically
revised.
The main changes are as follows:
— adding new viewing conditions P3/P4 for prints using CIE standard illuminant D50 with UV excluded;
— changing some tolerances according to the advance in lighting technology;
— introduced a colour fidelity index in response to the spread of LED lighting;
— removing the conditions for appraisal of images displayed on colour monitors.
This revision of ISO 3664:2009 meets the current needs of the Graphic Technology and Photographic
industries and minimizes differences between viewing equipment. It is noted that this revision contains
multiple specifications, each of which is appropriate to specific requirements. Users need to ensure that
they employ the specification which is appropriate to their application.
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
Introduction
While colour and density measurements play important roles in the control of colour reproduction, they
cannot replace the human observer for final assessment of the quality of complex images. Colour reflection
artwork, photographic transparencies, photographic prints, and photomechanical reproductions such as on-
press and off-press proofs, or press sheets, are commonly evaluated for their image and colour quality, or
compared critically with one another for fidelity of colour matching. Paper and other substrates contribute
to the colour appearance and controlling the colour of these is equally critical. However, it is noted that other
industries, such as the textile industry and the paper industry for unprinted paper, have their own set of
international standards which differ in illumination conditions from those recommended in this document.
There is no doubt that the best viewing condition for the visual assessment of colour is that in which the
product will be finally seen. Where this is known, and it is practical to do so, the various people in the
production chain can agree to use this viewing condition for all evaluation and comparison. However, it is
important that this is properly agreed upon in advance and that it is specified that such a viewing condition
is not ISO-defined.
Unfortunately, such agreement is often not practical. Even if a particular end-use condition is known, it can
be impract
...

FINAL DRAFT
International
Standard
ISO/FDIS 3664
ISO/TC 42
Graphic technology and
Secretariat: ANSI
photography — Viewing conditions
Voting begins on:
Technologie graphique et photographie — Conditions d'examen 2025-04-23
visuel
Voting terminates on:
2025-06-18
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/FDIS 3664:2025(en) © ISO 2025

FINAL DRAFT
ISO/FDIS 3664:2025(en)
International
Standard
ISO/FDIS 3664
ISO/TC 42
Graphic technology and
Secretariat: ANSI
photography — Viewing conditions
Voting begins on:
Technologie graphique et photographie — Conditions
d'examen visuel
Voting terminates on:
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2025
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO/FDIS 3664:2025(en) © ISO 2025

ii
ISO/FDIS 3664:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Viewing condition requirements. 5
4.1 General requirements .5
4.1.1 Applicability .5
4.1.2 Ambient conditions .5
4.1.3 Viewing apparatus .6
4.1.4 Spectral conditions for the reference illuminant .6
4.1.5 Maintenance .7
4.2 Conditions for critical comparison (ISO viewing conditions P1, P3, T1) .7
4.2.1 Applicability .7
4.2.2 Illumination .7
4.2.3 Illuminance (P1 and P3) .8
4.2.4 Surround and backing for reflection viewing (P1 and P3) .8
4.2.5 Luminance at the surface of the transparency illuminator (T1) .9
4.2.6 Transparency illuminator diffusion characteristics (T1) .9
4.2.7 Transparency surround (T1) .9
4.2.8 Relationship between transparency luminance and print illuminance (P1 or P3
and T1).9
4.3 Conditions for practical appraisal of prints (including routine inspection) (ISO viewing
condition P2 and P4) .10
4.3.1 Applicability .10
4.3.2 Illumination .10
4.3.3 Illuminance . . .10
4.3.4 Surround and backing .10
4.4 Conditions for viewing small transparencies by projection (ISO viewing conditions T2).11
4.4.1 Applicability .11
4.4.2 Illumination .11
4.4.3 Luminance .11
4.4.4 Uniformity of the projection screen luminance .11
4.4.5 Surround .11
4.4.6 Ambient light and veiling flare .11
4.4.7 Resolution .11
4.4.8 Distortion .11
5 Test methods .12
5.1 Spectral measurements . 12
5.2 Illuminance and luminance . 12
5.3 Resolution assessment for projection viewing apparatus . 12
Annex A (informative) Summary of viewing conditions specified in this document .13
Annex B (informative) Validity of requirements for reference viewing conditions for a print .15
Annex C (informative) Guidelines for judging and exhibiting photographs .18
Annex D (normative) Conformance test to UV content contained in illumination for P3 and P4
condition .20
Annex E (informative) Considerations for simultaneous comparison of samples between
multiple reference viewing environments .24
Bibliography .28

iii
ISO/FDIS 3664:2025(en)
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 Technical Committee ISO/TC 42, Photography, in collaboration with
Technical Committee ISO/TC 130, Graphic technology.
This fourth edition cancels and replaces the third edition (ISO 3664:2009), which has been technically
revised.
The main changes are as follows:
— adding new viewing conditions P3/P4 for prints using CIE standard illuminant D50 with UV excluded;
— changing some tolerances according to the advance in lighting technology;
— introduced a colour fidelity index in response to the spread of LED lighting;
— removing the conditions for appraisal of image displayed on colour monitor.
This revision of ISO 3664:2009 meets the current needs of the Graphic Technology and Photographic
industries and minimizes differences between viewing equipment. It is noted that this revision contains
multiple specifications, each of which is appropriate to specific requirements. Users need to ensure that
they employ the specification which is appropriate to their application.
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/FDIS 3664:2025(en)
Introduction
While colour and density measurements play important roles in the contro
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Secretariat: ANSI
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Graphic technology and photography — Viewing conditions
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Technologie graphique et photographie — Conditions d'examen visuel
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ISO/FDIS 3664:2025(en)
Formatted: Font: Bold
Formatted: HeaderCentered
Commented [eXtyles1]: The reference "ISO 2025" is to a
withdrawn standard
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
Formatted: Default Paragraph Font
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 Formatted: Default Paragraph Font
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
EmailE-mail: [e-mail]
Website: www.iso.orgwww.iso.org
Published in Switzerland
Formatted: Font: 10 pt
Formatted: Font: 10 pt
Formatted: Font: 11 pt
Formatted: FooterPageRomanNumber, Space After: 0
pt, Line spacing: single
ii © ISO 2022 2025 – All rights reserved
ii
ISO/FDIS 3664:2025(en)
Formatted: Font: 11 pt
Formatted: HeaderCentered, Left, Space After: 0 pt,
Line spacing: single, Tab stops: Not at 0.71 cm
Contents
Formatted: Adjust space between Latin and Asian text,
Adjust space between Asian text and numbers
Foreword . vi
Introduction . vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Viewing condition requirements . 5
4.1 General requirements . 5
4.2 Conditions for critical comparison (ISO viewing conditions P1, P3, T1) . 8
4.3 Conditions for practical appraisal of prints (including routine inspection) (ISO viewing
condition P2 and P4) . 11
4.4 Conditions for viewing small transparencies by projection (ISO viewing conditions T2) . 12
5 Test methods . 13
5.1 Spectral measurements . 13
5.2 Illuminance and luminance . 13
5.3 Resolution assessment for projection viewing apparatus . 14
Annex A (informative) Summary of viewing conditions specified in this document . 15
Annex B (informative) Validity of requirements for reference viewing conditions for a print . 18
Annex C (informative) Guidelines for judging and exhibiting photographs . 22
Annex D (normative) Conformance test to UV content contained in illumination for P3 and P4
condition . 24
Annex E (informative) Considerations for simultaneous comparison of samples between
multiple reference viewing environments . 29
Bibliography . 33

Foreword . v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Viewing condition requirements . 5
4.1 General requirements . 5
4.1.1 Applicability . 5
4.1.2 Ambient conditions . 5
4.1.3 Viewing apparatus . 6
4.1.4 Spectral conditions for the reference illuminant . 6
Formatted: Font: 10 pt
4.1.5 Maintenance . 7
Formatted: FooterCentered, Left, Space Before: 0 pt,
4.2 Conditions for critical comparison (ISO viewing conditions P1, P3, T1) . 7
Line spacing: single, Tab stops: Not at 17.2 cm
4.2.1 Applicability . 7
Formatted: Font: 11 pt
iii
ISO/FDIS 3664:2025(en)
Formatted: Font: Bold
Formatted: HeaderCentered
4.2.2 Illumination . 8
4.2.3 Illuminance (P1 and P3) . 8
4.2.4 Surround and backing for reflection viewing (P1 and P3) . 9
4.2.5 Luminance at the surface of the transparency illuminator (T1) . 9
4.2.6 Transparency illuminator diffusion characteristics (T1) . 9
4.2.7 Transparency surround (T1) . 9
4.2.8 Relationship between transparency luminance and print illuminance (P1 or P3 and T1)10
4.3 Conditions for practical appraisal of prints (including routine inspection) (ISO viewing
condition P2 and P4) . 10
4.3.1 Applicability . 10
4.3.2 Illumination . 10
4.3.3 Illuminance . 11
4.3.4 Surround and backing . 11
4.4 Conditions for viewing small transparencies by projection (ISO viewing conditions T2) . 11
4.4.1 Applicability . 11
4.4.2 Illumination . 11
4.4.3 Luminance . 11
4.4.4 Uniformity of the projection screen luminance . 11
4.4.5 Surround . 11
4.4.6 Ambient light and veiling flare . 11
4.4.7 Resolution . 11
4.4.8 Distortion . 12
5 Test methods . 12
5.1 Spectral measurements . 12
5.2 Illuminance and luminance . 12
5.3 Resolution assessment for projection viewing apparatus . 12
Annex A (informative) Summary of viewing conditions specified in this document . 13
Annex B (informative) Validity of requirements for reference viewing conditions for a print . 15
Annex C (informative) Guidelines for judging and exhibiting photographs . 18
C.1 General. 18
C.2 Recommendations . 19
Annex D (normative) Conformance test to UV content contained in illumination for P3 and P4
condition . 20
D.1 Background . 20
D.1.1 General. 20
D.1.2 Test method for M2 measurement condition . 20
D.1.3 Test method for P3 and P4 viewing condition . 21
D.1.3.1 General. 21
D.1.3.2 Test substrates . 21
D.1.3.3 Test filter . 21
D.1.3.4 Test procedure .
...