ISO/TS 20791-3:2023
(Main)Photography — Photographic reflection prints — Part 3: Evaluation of glossiness
Photography — Photographic reflection prints — Part 3: Evaluation of glossiness
This document describes the characterization of glossiness of photographic reflection prints, which consists of specular gloss measurement and image clarity measurement. This document is applicable to any photographic printing technology such as inkjet, thermal dye transfer, electrophotography and silver halide technologies. NOTE The level of preferred glossiness depends on the application.
Photographie — Tirages photographiques par réflexion — Partie 3: Évaluation de la brillance
General Information
Buy Standard
Standards Content (Sample)
TECHNICAL ISO/TS
SPECIFICATION 20791-3
First edition
2023-06
Photography — Photographic
reflection prints —
Part 3:
Evaluation of glossiness
Photographie — Tirages photographiques par réflexion —
Partie 3: Évaluation de la brillance
Reference number
ISO/TS 20791-3:2023(E)
© ISO 2023
---------------------- Page: 1 ----------------------
ISO/TS 20791-3:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
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: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
© ISO 2023 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TS 20791-3:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Terms. 1
3.2 Abbreviations . 2
4 Overview . 2
5 Sample preparations .2
5.1 Test targets . 2
5.2 Printing . 3
5.3 Specimens . 3
6 Measurement of specular gloss . 4
6.1 General . 4
6.2 Apparatus . 4
6.3 Procedure . 5
7 Measurement of image clarity . .5
7.1 General . 5
7.2 Apparatus . 5
7.3 Procedure . 6
8 Test report . 7
Annex A (informative) Other properties related to glossiness . 9
Bibliography .11
iii
© ISO 2023 – All rights reserved
---------------------- Page: 3 ----------------------
ISO/TS 20791-3:2023(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 42, Photography.
A list of all parts in the ISO 20791 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
© ISO 2023 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TS 20791-3:2023(E)
Introduction
Glossiness is an optical property regarding reflected light from print surfaces. Many studies have
been conducted on glossiness of industrial materials, and several studies have been reported on
print materials as well, see References [1] to [6]. It is especially important for photographic prints
with respect to printed image characteristic, because there is a wide variety from very high glossy
to dead matte surfaces. As stated in ISO/TR 20791-1, several properties affect the gloss perception of
photographic prints, see References [7]. Specular gloss and image clarity (distinctness of image) are
the two major properties among them. The former relates to the perceived intensity of reflected light
and the latter relates to the sharpness of reflected image. There is also a study stating that perceived
glossiness of photographic prints is well represented by the combination of these two measurements,
[8]
specular gloss and image sharpness .
Some measurements for properties regarding glossiness have been standardized for industrial
materials such as coatings, plastics and papers, see References [9] to [12] and ISO 17221. Among them,
the measurement methods for coatings are standardized with specular gloss and image clarity as
important properties for the reflection characteristics. Some standards for graphic printing and office
[13]
printing basically refer to them while adding methods and cautions specific to each application
[14]
. But there has been no published standard for measuring both specular gloss and image clarity for
photographic prints.
This document provides the measurement methods of two major properties to evaluate glossiness
of photographic prints: specular gloss and image clarity. The methods are based on the existing
documents for coatings and plastics, and specific requirements for photographic prints are defined
regarding sample preparation, measurement procedure and reporting.
v
© ISO 2023 – All rights reserved
---------------------- Page: 5 ----------------------
TECHNICAL SPECIFICATION ISO/TS 20791-3:2023(E)
Photography — Photographic reflection prints —
Part 3:
Evaluation of glossiness
1 Scope
This document describes the characterization of glossiness of photographic reflection prints, which
consists of specular gloss measurement and image clarity measurement. This document is applicable
to any photographic printing technology such as inkjet, thermal dye transfer, electrophotography and
silver halide technologies.
NOTE The level of preferred glossiness depends on the application.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 2813, Paints and varnishes — Determination of gloss value at 20°, 60° and 85°
ISO 17221, Plastics — Determination of image clarity (degree of sharpness of reflected or transmitted
image)
ISO 18913, Imaging materials — Permanence — Vocabulary
3 Terms and definitions
For the purposes of this document, the following terms and definitions given in ISO 18913 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1 Terms
3.1.1
glossiness
visual characteristic related to shiny and smooth appearance
Note 1 to entry: Based on this appearance, humans perceive features such as reflection characteristics and
roughness of the surface of an object.
3.1.2
specular gloss
ratio of the luminous flux, reflected by the test surface into a specified aperture at the angle of specular
reflection, to that from a standard specularly reflecting surface under the same conditions
[SOURCE: ISO 4046-5:2016, 5.107, modified — Note 1 to entry was deleted.]
1
© ISO 2023 – All rights reserved
---------------------- Page: 6 ----------------------
ISO/TS 20791-3:2023(E)
3.1.3
image clarity
distinctness of image
DOI
degree of sharpness of an image reflected by a specimen or transmitted through a specimen
[SOURCE: ISO 17221:2014, 3.1, modified — the synonym "distinctness of image (DOI)" was added and
Note 1 to entry was deleted.]
3.2 Abbreviations
C cyan
M magenta
Y yellow
R red
G green
B blue
4 Overview
This document stipulates evaluation methods of glossiness, based on specular gloss and image clarity.
Each measurement method is based on ISO 2813 and ISO 17221 respectively. Specific requirements for
photographic prints are described in Clause 5 for sample preparation, Clause 6 and 7 for measurement
and Clause 8 for reporting. In addition, other properties which relate to glossiness are described in
Annex A.
The purpose of this document is to characterize the glossiness of photographic prints. Since the level
of preferred glossiness depends on the application, this document does not discuss performance
superiority or inferiority. The methods in this document are intended to be used for product design and
product comparison and are not intended to be used for daily quality assurance in manufacturing.
5 Sample preparations
5.1 Test targets
At least white (D ) and black patches shall be printed for measurement. Additional colours such as
min
cyan (C), magenta (M), yellow (Y), red (R), green (G), blue (B) and grey are recommended to evaluate
the effects of colour or density on measured properties. The sRGB encoded patch values described in
ISO 18944 can be applied to test targets for digital printers. Patch size for measurements shall be not
less than 25 mm × 25 mm. Examples of test targets are shown in Figure 1. Figure 1 a) can be used for
both colour and monochrome prints.
NOTE A larger patch size is sometimes necessary for the measurements of specular gloss especially at a
higher angle such as 85°. The manufacturer of each measuring instrument usually provides information about
the aperture size and/or the minimum patch size.
2
© ISO 2023 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/TS 20791-3:2023(E)
a) grey step patches b) C, M, Y, R, G, B colour patches
Figure 1 — Examples of test targets
5.2 Printing
The standard ambient environmental condition for printing shall be a temperature of 23 °C ± 3 °C,
and a relative humidity of 50 % RH ± 10 % RH unless it has been confirmed that the temperature and
humidity do not affect the properties related to gloss. If it is not possible to conduct the test under the
standard environmental condition, the temperature and humidity shall be reported.
Aqueous and solvent inkjet prints, and prints of any type that require curing/stabilization/dry-down
shall be conditioned until the curing process is finished. If the duration of curing is unknown, prints
should be conditioned for at least two weeks after printing, in an environment with a temperature of
23 °C ± 2 °C, with a relative humidity of 50 % RH ± 5 % RH.
5.3 Specimens
The size of specimen shall not be less than 30 mm × 30 mm to cover the minimum size of 25 mm × 25 mm
for a single test patch.
In the case of large size prints, they are cut to fit the above size before measurement.
NOTE The
...
ISO/DTS 20791-3 2022(E)
Style Definition: Heading 1: Indent: Left: 0 pt, First
line: 0 pt, Tab stops: Not at 21.6 pt
Date: 2022-08-17
Style Definition: Heading 2: Font: Bold, Tab stops: Not
at 18 pt
ISO TC 42/WG 3
Style Definition: Heading 3: Font: Bold
Secretariat: ANSI
Style Definition: Heading 4: Font: Bold
Style Definition: Heading 5: Font: Bold
Photography – Photographic reflection prints – Part 3: Evaluation of glossiness
Style Definition: Heading 6: Font: Bold
Photographie — Tirages photographiques par réflexion — Part 3: Évaluation de la brillance
Style Definition: ANNEX
Style Definition: AMEND Terms Heading: Font: Bold
Style Definition: AMEND Heading 1 Unnumbered:
Font: Bold
---------------------- Page: 1 ----------------------
ISO/DTS 20791-3:2022(E)
© ISO 2022
Formatted: Pattern: Clear
Formatted: Pattern: Clear
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: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.orgwww.iso.org
Published in Switzerland
ii © ISO 2022 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/DTS 20791-3:2022(E)
Contents
Foreword . ii
Introduction . ii
1 Scope . 2
2 Normative references . 2
3 Terms and definitions . 2
3.1 Terms . 2
3.2 Abbreviations . 2
4 Overview . 2
5 Sample preparations . 2
5.1 Test targets . 2
5.2 Printing . 2
5.3 Specimens . 2
6 Measurement of specular gloss . 2
6.1 General . 2
6.2 Apparatus . 2
6.3 Procedure . 2
7 Measurement of image clarity . 2
7.1 General . 2
7.2 Apparatus . 2
7.3 Procedure . 2
8 Test report . 2
Annex A (informative) Other properties regarding glossiness . 2
A.1 General . 2
A.2 Differential gloss . 2
A.3 Gloss colour (bronzing) . 2
A.4 Relief . 2
A.5 Gloss streak and other gloss non-uniformity . 2
Bibliography . 2
Foreword . ii
Introduction . ii
© ISO 2022 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/DTS 20791-3:2022(E)
1 Scope . 2
2 Normative references . 2
3 Terms and definitions . 2
3.1 Terms . 2
3.2 Abbreviations . 2
4 Overview . 2
5 Sample preparations . 2
5.1 Test targets . 2
5.2 Printing . 2
5.3 Specimens . 2
6 Measurement of specular gloss . 2
6.1 General . 2
6.2 Apparatus . 2
6.3 Procedure . 2
7 Measurement of image clarity . 2
7.1 General . 2
7.2 Apparatus . 2
7.3 Procedure . 2
8 Test report . 2
Annex A (informative) Other properties regarding glossiness . 2
Bibliography . 2
iv © ISO 2022 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/DTS 20791-3:2022(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/directiveswww.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/patentswww.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.htmlwww.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 42, Photography.
A list of all parts in the ISO 20791 series can be found on the ISO website.
Formatted: Pattern: Clear
Formatted: Pattern: Clear
Any feedback or questions on this document should be directed to the user’s national standards body. A
Formatted: Pattern: Clear
complete listing of these bodies can be found at
www.iso.org/members.htmlwww.iso.org/members.html.
© ISO 2022 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO/DTS 20791-3:2022(E)
Introduction
Glossiness is an optical property regarding reflected light from print surfaces. Many studies have been
conducted on glossiness of industrial materials, and several studies have been reported on print
[1] [6]
materials as well. - , see References [1] to [6]. It is especially important for photographic prints with
respect to printed image quality, because it has wide variety from very high glossy to dead matte
[7]
surfaces. As stated in ISO /TR 20791-1, , several properties affect the gloss perception of photographic
Formatted: Pattern: Clear
prints. Specular gloss and image clarity (distinctness of image) are the two major properties among
Formatted: Pattern: Clear
them. The former relates to the perceived intensity of reflected light and the latter relates to the
Formatted: Pattern: Clear
sharpness of reflected image. There is also a study that states that perceived glossiness of photographic
prints is well represented by the combination of these two measurements, specular gloss and image
Formatted: Pattern: Clear
[8]
sharpness .
Formatted: Pattern: Clear
Some measurements for properties regarding glossiness have been standardized for industrial
[9] [13]
materials such as coating, plastics and papers. - , see References [9] to [13]. Among them, the
measurement methods for coatings are standardized with specular gloss and image clarity as important
properties for the reflection characteristics. Some standards for graphic printing and office printing
[[14][15]]
basically refer to them while adding methods and cautions specific to each application. . But there
Formatted: Pattern: Clear
has been no published standard for photographic prints.
Formatted: Pattern: Clear
This document provides the measurement methods of two major properties to evaluate glossiness of
photographic prints: specular gloss and image clarity. The methods are based on the existing
documents for coatings and plastics, and specific requirements for photographic prints are defined
regarding sample preparation, measurement procedure and reporting.
vi © ISO 2022 – All rights reserved
---------------------- Page: 6 ----------------------
TECHNICAL SPECIFICATION ISO/DTS 20791-3:2022(E)
Photography – Photographic reflection prints – Part 3: Evaluation
of glossiness
1 Scope
This document describes the characterization of glossiness of photographic reflection prints, which
consists of specular gloss measurement and image clarity measurement. This document is applicable to
any photographic printing technologies such as inkjet, thermal dye transfer, electrophotography and
silver halide technologies.
NOTE The level of preferred glossiness depends on the application.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 2813, Paints and varnishes — Determination of gloss value at 20°, 60° and 85°
ISO 17221, Plastics — Determination of image clarity (degree of sharpness of reflected or
transmitted image)
ISO 18913, Imaging materials — Permanence — Vocabulary
ISO 2813, Paints and varnishes — Determination of gloss value at 20°, 60° and 85°
ISO 17221, Plastics — Determination of image clarity (degree of sharpness of reflected or transmitted
image)
ISO 18913, Imaging materials — Permanence — Vocabulary
3 Terms and definitions
For the purposes of this document, the following terms and definitions given in ISO 18913 and the
Formatted: Pattern: Clear
following apply.
Formatted: Pattern: Clear
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/
3.1 Terms
3.1.1
glossiness
visual quality related to shiny and smooth appearance
© ISO 2022 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO/DTS 20791-3:2022(E)
Note 1 to entry: Based on this appearance, humans perceive features such as reflection characteristics and
roughness of the surface of an object.
3.1.2
specular gloss
ratio of the luminous flux, reflected by the test surface into a specified aperture at the angle of specular
reflection, to that from a standard specularly reflecting surface under the same conditions
[SOURCE: ISO 4046-5:2016, 5.107, modified — Note 1 to entry was deleted.]
Formatted: Pattern: Clear
Formatted: Pattern: Clear
3.1.3
Formatted: Pattern: Clear
image clarity
distinctness of image
Formatted: Pattern: Clear
DOI
Formatted: Pattern: Clear
degree of sharpness of an image reflected by a specimen or transmitted through a specimen
[SOURCE: ISO 17221:2014, 3.1, modified — the synonym "distinctness of image (DOI)" was added and
Formatted: Pattern: Clear
Note 1 to entry was deleted.]
Formatted: Pattern: Clear
Formatted: Pattern: Clear
3.2 Abbreviations
Formatted: Pattern: Clear
C cyan
M magenta
Y yellow
R red
G green
B blue
4 Overview
This document stipulates evaluation methods of glossiness, based on specular gloss and image clarity.
Each measurement method is based on ISO 2813 and ISO 17221. Specific requirements for
Formatted: Pattern: Clear
photographic prints are described in Clause 5 for sample preparation, Clause 6 and 7 for measurement
Formatted: Pattern: Clear
and Clause 8 for reporting. In addition, other properties which relate to glossiness are described in
Formatted: Pattern: Clear
Annex A.
Formatted: Pattern: Clear
The purpose of this document is to characterize the glossiness of photographic prints. Since the level of
preferred glossiness depends on the application, this document does not discuss performance
Formatted: Pattern: Clear
superiority or inferiority. The methods in this document are intended to be used for product design and
Formatted: Pattern: Clear
product comparison and are not intended to be used for daily quality assurance in manufacturing.
Formatted: Pattern: Clear
Formatted: Pattern: Clear
5 Sample preparations
5.1 Test targets
At least white (Dmin) and black patches shall be printed for measurement. Additional colours such as
Formatted: Font: Italic
cyan (C), magenta (M), yellow (Y), red (R), green (G), blue (B) and grey are recommended to evaluate
the effects of colour or density on measured properties. The sRGB encoded patch values described in
ISO 18944 can be applied to test targets for digital printers. Patch size for measurements shall be not
Formatted: Pattern: Clear
Formatted: Pattern: Clear
2 © ISO 2022 – All rights reserved
---------------------- Page: 8 ----------------------
ISO/DTS 20791-3:2022(E)
less than 25 mm x 25 mm. Examples of test targets are shown in Figure 1. Figure 1 ( a) can be used for
Formatted: Pattern: Clear
both colour and monochrome prints.
Formatted: Pattern: Clear
NOTE A larger patch size is sometimes necessary for the measurements of specular gloss especially at higher
Formatted: cite_fig
angle such as 85°. The manufacturer of each measuring instrument usually provides information about the
aperture size and/or the minimum patch size.
20791-3_ed1fig1a.EPS 20791-3_ed1fig1b.EPS
(a)a) grey step patches (b)b) C, M, Y, R, G, B colour patches
Formatted: Table body (+), Adjust space between Latin
and Asian text, Adjust space between Asian text and
numbers
Figure 1 — Examples of test targets: (a) grey step patches, (b) C, M, Y, R, G, B colour patches
Formatted: French (Switzerland)
5.2 Printing
The standard ambient environmental condition for printing shall be a temperature of 23 °C ± 3 °C, a
relative humidity of 50 % RH ± 10 % RH and an air pressure of 101 kPa ± 20 kPa. If it is not possible to
conduct the test under the standard environmental condition, the temperature and humidity shall be
reported.
Aqueous and solvent inkjet prints, and prints of any type that require curing/stabilization/dry-down
shall be conditioned until the curing process is finished. If the duration of curing is unknown, prints
should be conditioned for at least two weeks after printing, in an environment with a temperature of
23 °C ± 2 °C
...
FINAL
TECHNICAL ISO/DTS
DRAFT
SPECIFICATION 20791-3
ISO/TC 42
Photography — Photographic
Secretariat: ANSI
reflection prints —
Voting begins on:
2022-09-08
Part 3:
Voting terminates on:
Evaluation of glossiness
2022-11-03
Photographie — Tirages photographiques par réflexion —
Partie 3: Évaluation de la brillance
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
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/DTS 20791-3:2022(E)
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. © ISO 2022
---------------------- Page: 1 ----------------------
ISO/DTS 20791-3:2022(E)
FINAL
TECHNICAL ISO/DTS
DRAFT
SPECIFICATION 20791-3
ISO/TC 42
Photography — Photographic
Secretariat: ANSI
reflection prints —
Voting begins on:
Part 3:
Voting terminates on:
Evaluation of glossiness
Photographie — Tirages photographiques par réflexion —
Partie 3: Évaluation de la brillance
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022
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.
RECIPIENTS OF THIS DRAFT ARE INVITED TO
ISO copyright office
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
CP 401 • Ch. de Blandonnet 8
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
CH-1214 Vernier, Geneva
DOCUMENTATION.
Phone: +41 22 749 01 11
IN ADDITION TO THEIR EVALUATION AS
Reference number
Email: copyright@iso.org
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/DTS 20791-3:2022(E)
Website: www.iso.org
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
Published in Switzerland
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
ii
© ISO 2022 – All rights reserved
NATIONAL REGULATIONS. © ISO 2022
---------------------- Page: 2 ----------------------
ISO/DTS 20791-3:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Terms. 1
3.2 Abbreviations . 2
4 Overview . 2
5 Sample preparations .2
5.1 Test targets . 2
5.2 Printing . 3
5.3 Specimens . 3
6 Measurement of specular gloss . 4
6.1 General . 4
6.2 Apparatus . 4
6.3 Procedure . 4
7 Measurement of image clarity . .5
7.1 General . 5
7.2 Apparatus . 5
7.3 Procedure . 6
8 Test report . 7
Annex A (informative) Other properties regarding glossiness . 9
Bibliography .11
iii
© ISO 2022 – All rights reserved
---------------------- Page: 3 ----------------------
ISO/DTS 20791-3:2022(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 42, Photography.
A list of all parts in the ISO 20791 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
© ISO 2022 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/DTS 20791-3:2022(E)
Introduction
Glossiness is an optical property regarding reflected light from print surfaces. Many studies have
been conducted on glossiness of industrial materials, and several studies have been reported on print
materials as well, see References [1] to [6]. It is especially important for photographic prints with
respect to printed image quality, because it has wide variety from very high glossy to dead matte
surfaces. As stated in ISO/TR 20791-1, several properties affect the gloss perception of photographic
prints. Specular gloss and image clarity (distinctness of image) are the two major properties among
them. The former relates to the perceived intensity of reflected light and the latter relates to the
sharpness of reflected image. There is also a study that states that perceived glossiness of photographic
prints is well represented by the combination of these two measurements, specular gloss and image
[8]
sharpness .
Some measurements for properties regarding glossiness have been standardized for industrial
materials such as coating, plastics and papers, see References [9] to [13]. Among them, the measurement
methods for coatings are standardized with specular gloss and image clarity as important properties
for the reflection characteristics. Some standards for graphic printing and office printing basically
[14][15]
refer to them while adding methods and cautions specific to each application . But there has been
no published standard for photographic prints.
This document provides the measurement methods of two major properties to evaluate glossiness
of photographic prints: specular gloss and image clarity. The methods are based on the existing
documents for coatings and plastics, and specific requirements for photographic prints are defined
regarding sample preparation, measurement procedure and reporting.
v
© ISO 2022 – All rights reserved
---------------------- Page: 5 ----------------------
TECHNICAL SPECIFICATION ISO/DTS 20791-3:2022(E)
Photography — Photographic reflection prints —
Part 3:
Evaluation of glossiness
1 Scope
This document describes the characterization of glossiness of photographic reflection prints, which
consists of specular gloss measurement and image clarity measurement. This document is applicable
to any photographic printing technologies such as inkjet, thermal dye transfer, electrophotography and
silver halide technologies.
NOTE The level of preferred glossiness depends on the application.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 2813, Paints and varnishes — Determination of gloss value at 20°, 60° and 85°
ISO 17221, Plastics — Determination of image clarity (degree of sharpness of reflected or transmitted
image)
ISO 18913, Imaging materials — Permanence — Vocabulary
3 Terms and definitions
For the purposes of this document, the following terms and definitions given in ISO 18913 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1 Terms
3.1.1
glossiness
visual quality related to shiny and smooth appearance
Note 1 to entry: Based on this appearance, humans perceive features such as reflection characteristics and
roughness of the surface of an object.
3.1.2
specular gloss
ratio of the luminous flux, reflected by the test surface into a specified aperture at the angle of specular
reflection, to that from a standard specularly reflecting surface under the same conditions
[SOURCE: ISO 4046-5:2016, 5.107, modified — Note 1 to entry was deleted.]
1
© ISO 2022 – All rights reserved
---------------------- Page: 6 ----------------------
ISO/DTS 20791-3:2022(E)
3.1.3
image clarity
distinctness of image
DOI
degree of sharpness of an image reflected by a specimen or transmitted through a specimen
[SOURCE: ISO 17221:2014, 3.1, modified — the synonym "distinctness of image (DOI)" was added and
Note 1 to entry was deleted.]
3.2 Abbreviations
C cyan
M magenta
Y yellow
R red
G green
B blue
4 Overview
This document stipulates evaluation methods of glossiness, based on specular gloss and image clarity.
Each measurement method is based on ISO 2813 and ISO 17221. Specific requirements for photographic
prints are described in Clause 5 for sample preparation, Clause 6 and 7 for measurement and Clause 8
for reporting. In addition, other properties which relate to glossiness are described in Annex A.
The purpose of this document is to characterize the glossiness of photographic prints. Since the level
of preferred glossiness depends on the application, this document does not discuss performance
superiority or inferiority. The methods in this document are intended to be used for product design and
product comparison and are not intended to be used for daily quality assurance in manufacturing.
5 Sample preparations
5.1 Test targets
At least white (D ) and black patches shall be printed for measurement. Additional colours such as
min
cyan (C), magenta (M), yellow (Y), red (R), green (G), blue (B) and grey are recommended to evaluate
the effects of colour or density on measured properties. The sRGB encoded patch values described in
ISO 18944 can be applied to test targets for digital printers. Patch size for measurements shall be not
less than 25 mm x 25 mm. Examples of test targets are shown in Figure 1. Figure 1 a) can be used for
both colour and monochrome prints.
NOTE A larger patch size is sometimes necessary for the measurements of specular gloss especially at
higher angle such as 85°. The manufacturer of each measuring instrument usually provides information about
the aperture size and/or the minimum patch size.
2
© ISO 2022 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/DTS 20791-3:2022(E)
a) grey step patches b) C, M, Y, R, G, B colour patches
Figure 1 — Examples of test targets
5.2 Printing
The standard ambient environmental condition for printing shall be a temperature of 23 °C ± 3 °C, a
relative humidity of 50 % RH ± 10 % RH and an air pressure of 101 kPa ± 20 kPa. If it is not
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.