EN ISO 9241-306:2018

Ergonomics of human-system interaction - Part 306: Field assessment methods for electronic visual displays (ISO 9241-306:2018)

This document establishes optical, geometrical and visual inspection methods for the assessment of a display in various contexts of use according to ISO 9241‑303.

Ergonomie der Mensch-System-Interaktion - Teil 306: Vor-Ort-Bewertungsverfahren für elektronische optische Anzeigen (ISO 9241-306:2018)

Ergonomie de l'interaction homme-système - Partie 306: Méthodes d'appréciation sur le terrain des écrans de visualisation électroniques (ISO 9241-306:2018)

Le présent document établit les méthodes d'ajustement optique, géométrique et visuel pour l'évaluation d'un dispositif d'affichage dans divers contextes d'utilisation conformément à l'ISO 9241‑303.

Ergonomija medsebojnega vpliva človek-sistem - 306. del: Metode ocenjevanja polja elektronskih slikovnih zaslonov (ISO 9241-306:2018)

Ta dokument obravnava vse pomembne nevarnosti, nevarne okoliščine ter dogodke iz točke 4 v zvezi z odsesovalnimi sistemi za lesne odrezke in prah za notranjo uporabo, ki so predvideni za priključitev na stroje, zasnovane za rezanje masivnega lesa (vključno s trdim lesom), lesnih materialov ter lesu podobnih materialov, kadar se uporabljajo v skladu s predvidenim namenom in v pogojih, ki jih predvidi proizvajalec, vključno z razumno pričakovano nepravilno uporabo.
Ta evropski standard se ne uporablja za:
a) odsesovalne sisteme z nazivnim pretokom nad 8000 m³/h in/ali prostornino s prahom obremenjenega predela izločevalnika prahu nad 3,5 m³;
b) sesalnike v skladu s standardom EN 60335-2-69/A2:2013;
c) odsesovalne sisteme z ventilatorji, nameščenimi v predelu, obremenjenem s prahom;
d) odsesovalno opremo (npr. odsesovalni pokrovi, vodi) v notranjosti lesnoobdelovalnega stroja, tj. do in vključno z odvodom, na katerega je priključen odsesovalni sistem;
e) odsesovalne sisteme, zasnovane za prah z vrednostmi KST nad 200 bar ms-1, najmanjšo vžigno energijo pod 10 mJ in/ali nižjo stopnjo eksplozivnosti pod 30 g/m³;
f) odsesovalne sisteme, zasnovane za aspiracijo eksplozivnih atmosfer, npr. obremenitev prahu > 50 % nižje stopnje eksplozivnosti;
g) sisteme, zasnovane za izločanje iz strojev z večjim tveganjem povzročitve virov vžiga;
h) silose.
Ta evropski standard se ne uporablja za stroje, ki so bili proizvedeni pred objavo tega dokumenta kot standarda EN.

General Information

• Status: Published
• Publication Date: 11-Sep-2018
• Withdrawal Date: 30-Mar-2019
• ICS: 13.180 - Ergonomics
• ICS: 35.180 - IT Terminal and other peripheral equipment
• Technical Committee: CEN/TC 122 - Ergonomics
• Drafting Committee: CEN/TC 122/WG 5 - Ergonomics of human-computer interaction
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 12-Sep-2018
• Completion Date: 12-Sep-2018
• Ref Project: SIST EN ISO 9241-306:2018 - Ergonomics of human-system interaction - Part 306: Field assessment methods for electronic visual displays (ISO 9241-306:2018)

Relations

• Replaces: EN ISO 9241-306:2008 - Ergonomics of human-system interaction - Part 306: Field assessment methods for electronic visual displays (ISO 9241-306:2008)
• Effective Date: 19-Sep-2018

Overview

EN ISO 9241-306:2018 - Ergonomics of human-system interaction - Part 306: Field assessment methods for electronic visual displays (ISO 9241-306:2018) defines on-site optical, geometrical and visual inspection methods for assessing electronic visual displays. Published by CEN as an adoption of ISO 9241-306:2018, this standard supports practical, real-world evaluation of displays in their actual contexts of use and aligns with the requirements of ISO 9241‑303.

Key topics and technical requirements

The standard provides structured, field-oriented methods and criteria for assessing display performance, including:

• Preparation for assessment
  • Cleaning, physical set-up, display warm-up and control settings prior to measurement.
• Viewing conditions
  • Design viewing distance and direction, gaze and head tilt angles, and assessment of virtual image displays.
• Luminance and lighting
  • Measurement and evaluation of ambient illuminance, display luminance, luminance balance, glare and luminance adjustment capability.
• Special environments
  • Considerations for vibration, wind/rain exposure and extreme temperatures that affect display performance in the field.
• Visual artefacts
  • Identification and inspection of luminance, colour and contrast non-uniformity, geometric distortions, pixel faults, flicker, jitter, moiré and unwanted reflections.
• Legibility and readability
  • Assessment of luminance contrast, image polarity, character height, stroke width, spacing (between characters, words, lines), text size constancy and overall readability.
• Information coding and graphics
  • Legibility of luminance, blink and colour coding, geometry-based coding, and graphic object size/contrast considerations.
• Fidelity and performance
  • Grey-scale/gamma behaviour, moving-image rendering, colour misconvergence, image formation time and spatial resolution.
• Other practical considerations
  • Surface isotropy/anisotropy, viewing angle ranges, adjustability and controllability of the display system.

Applications and who uses it

EN ISO 9241-306 is intended for professionals who require reliable, repeatable on-site assessment of display ergonomics and visual performance:

• Ergonomists and human factors specialists
• Display and monitor manufacturers
• System integrators (control rooms, vehicle cockpits, medical devices)
• Quality assurance and test laboratories
• Procurement teams and regulatory bodies evaluating compliance
• UI/UX designers and software engineers working with embedded or industrial displays

Practical applications include site acceptance testing, incident investigations, usability validation in operational contexts, and compliance checks against ISO 9241‑303 requirements.

Related standards

• ISO 9241 series (ergonomics of human-system interaction), notably ISO 9241‑303 (requirements for electronic visual displays). Use EN ISO 9241-306 alongside ISO 9241-303 for complete specification and conformance workflows.

Keywords: ergonomics, human-system interaction, field assessment, electronic visual displays, ISO 9241-306, display assessment, luminance, legibility, visual artefacts, viewing conditions.

Standards Content (Sample)

SLOVENSKI STANDARD
01-december-2018
1DGRPHãþD
SIST EN ISO 9241-306:2009
(UJRQRPLMDPHGVHERMQHJDYSOLYDþORYHNVLVWHPGHO0HWRGHRFHQMHYDQMD
SROMDHOHNWURQVNLKVOLNRYQLK]DVORQRY,62
Ergonomics of human-system interaction - Part 306: Field assessment methods for
electronic visual displays (ISO 9241-306:2018)
Ergonomie der Mensch-System-Interaktion - Teil 306: Vor-Ort-Bewertungsverfahren für
elektronische optische Anzeigen (ISO 9241-306:2018)
Ergonomie de l'interaction homme-système - Partie 306: Méthodes d'appréciation sur le
terrain des écrans de visualisation électroniques (ISO 9241-306:2018)
Ta slovenski standard je istoveten z: EN ISO 9241-306:2018
ICS:
13.180 Ergonomija Ergonomics
35.180 Terminalska in druga IT Terminal and other
periferna oprema IT peripheral equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 9241-306
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2018
EUROPÄISCHE NORM
ICS 13.180; 35.180 Supersedes EN ISO 9241-306:2008
English Version
Ergonomics of human-system interaction - Part 306: Field
assessment methods for electronic visual displays (ISO
9241-306:2018)
Ergonomie de l'interaction homme-système - Partie Ergonomie der Mensch-System-Interaktion - Teil 306:
306: Méthodes d'appréciation sur le terrain des écrans Vor-Ort-Bewertungsverfahren für elektronische
de visualisation électroniques (ISO 9241-306:2018) optische Anzeigen (ISO 9241-306:2018)
This European Standard was approved by CEN on 3 August 2018.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 9241-306:2018 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 9241-306:2018) has been prepared by Technical Committee ISO/TC 153
"Valves" in collaboration with Technical Committee CEN/TC 122 “Ergonomics” the secretariat of which
is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by March 2019, and conflicting national standards shall
be withdrawn at the latest by March 2019.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 9241-306:2008.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 9241-306:2018 has been approved by CEN as EN ISO 9241-306:2018 without any
modification.
INTERNATIONAL ISO
STANDARD 9241-306
Second edition
2018-08
Ergonomics of human-system
interaction —
Part 306:
Field assessment methods for
electronic visual displays
Ergonomie de l'interaction homme-système —
Partie 306: Méthodes d'appréciation sur le terrain des écrans de
visualisation électroniques
Reference number
ISO 9241-306:2018(E)
©
ISO 2018
ISO 9241-306:2018(E)
© ISO 2018
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]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

ISO 9241-306:2018(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Preparation for assessment . 1
4.1 Cleaning . 1
4.2 Set-up . 1
4.3 Display warm-up . 2
4.4 Control settings of the visual display . 2
5 Assessment methods . 3
5.1 Viewing conditions . 3
5.1.1 Design viewing distance . 3
5.1.2 Design viewing direction . 4
5.1.3 Gaze and head tilt angles . 5
5.1.4 Virtual images . 5
5.2 Luminance . 5
5.2.1 Illuminance . 5
5.2.2 Display luminance . 5
5.2.3 Luminance balance and glare . 5
5.2.4 Luminance adjustment . 6
5.3 Special physical environments . 6
5.3.1 Vibration . 6
5.3.2 Wind and rain . 6
5.3.3 Excessive temperatures . 6
5.4 Visual artefacts . 6
5.4.1 Luminance non-uniformity . 6
5.4.2 Colour non-uniformity . 6
5.4.3 Contrast non-uniformity . 7
5.4.4 Geometric distortions . 7
5.4.5 Pixel faults . 7
5.4.6 Temporal instability (flicker) . 7
5.4.7 Spatial instability (jitter) . 7
5.4.8 Moiré effects . 7
5.4.9 Other instabilities. 8
5.4.10 Unwanted reflections . 8
5.4.11 Unintended depth effects . 8
5.5 Legibility and readability . 8
5.5.1 Luminance contrast . 8
5.5.2 Image polarity . 8
5.5.3 Character height . 9
5.5.4 Text size constancy .10
5.5.5 Character stroke width .10
5.5.6 Character width-to-height ratio .10
5.5.7 Character format .10
5.5.8 Between-character spacing .10
5.5.9 Between-word spacing .10
5.5.10 Between-line spacing .10
5.6 Legibility of information coding .10
5.6.1 Luminance coding .10
5.6.2 Absolute luminance coding .10
5.6.3 Blink coding .11
ISO 9241-306:2018(E)
5.6.4 Colour coding .11
5.6.5 Geometrical coding .11
5.7 Legibility of graphics.11
5.7.1 Monochrome and multicolour object size .11
5.7.2 Contrast for object legibility .11
5.7.3 Grey and colour considerations for graphics .11
5.7.4 Background and surround image effects .11
5.7.5 Number of colours .11
5.8 Fidelity .12
5.8.1 Grey scale and gamma . .12
5.8.2 Rendering of moving images .12
5.8.3 Colour misconvergence .12
5.8.4 Image formation time (IFT) .12
5.8.5 Spatial resolution .13
6 Other considerations .13
6.1 Isotropic surface .13
6.2 Anisotropic surfaces .13
6.3 Viewing angle range .13
6.4 Adjustability .13
6.5 Controllability .13
6.6 Luminous environment .14
Annex A (informative) Overview of the ISO 9241 series .15
Annex B (informative) Influences on ergonomics parameters of visual displays .16
Annex C (informative) Unwanted reflections .19
Annex D (informative) Definition and application of test charts for display output
linearization for eight different ambient light reflections at office work places .22
Annex E (informative) Considerations for Cathode ray tube (CRT) displays .53
Bibliography .55
iv © ISO 2018 – All rights reserved

ISO 9241-306:2018(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 159, Ergonomics, Subcommittee SC 4,
Ergonomics of human-system interaction.
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.
This second edition cancels and replaces the first edition (ISO 9241-306:2008), which has been
technically revised. The main changes compared to the previous edition are as follows:
— cathode ray tubes (CRT) displays have been added to a new informative Annex E;
— definitions of five chromatic text charts for elementary or device hue output have been added to
Annex D.
A list of all parts in the ISO 9241 series can be found on the ISO website.
ISO 9241-306:2018(E)
Introduction
This document is part of the ISO 9241 series which establishes requirements for the ergonomic design
of electronic visual displays. At the same time, this “300” subseries replaces either partially or fully
certain previously published parts of ISO 9241 as well as several other International Standards (see the
Forewords of the respective parts for the details).
— An introduction to the subseries is given by ISO 9241-300.
— Terms and definitions related to electronic visual displays have been transferred to, and collected
in, ISO 9241-302.
— While the areas previously covered in ISO 9241 and by ISO 13406 remain essentially unchanged, test
methods and requirements have been updated to account for advances in science and technology.
— All generic ergonomic requirements have been incorporated into ISO 9241-303.
— The application of those requirements to different display technologies, application areas and
environmental conditions — including test methods and pass/fail criteria — are specified in
ISO 9241-307.
— Methods for performing formal display measurements to determine display characteristics and
verify technical specifications (tests that can be very costly and time-consuming and that are
normally performed under rigorous test conditions with a new device) are given in ISO 9241-305
and ISO 9241-307.
— In addition, guidance on the design of SED (surface-conduction electron-emitter displays) and OLED
(organic light-emitting diode) displays is given in ISO/TR 9241-308 and ISO/TR 9241-309.
The overall modular structure of the subseries facilitates its revision and amendment, as ongoing
technological development enables new forms of display interaction.
This document is concerned with ergonomic workplace assessment and is aimed at providing a means
of assessing whether or not the visual ergonomic requirements specified in ISO 9241-303 are satisfied
within a specified task setting. The intention is not necessarily to produce a perfect display with
optimum visual characteristics, but rather to ensure that the needed qualities to perform the visual
task satisfactorily are indeed present.
During the lifetime of a display, the context in which it is used can often vary; “ageing” normally takes
place as the display is used and, as a result, the performance of the display can be reduced over time.
The lighting conditions under which a display is used also often vary.
In actual VDT workstation use, the main ergonomic concerns are the visual task being performed and
the input devices being used to accomplish the task.
There are several factors that make the performance of a visual task using a VDT different from that in
many other non-VDT or paper tasks. These factors are related to the positioning of the various elements
needed for performing the visual task.
The ergonomic goal is to be able to read the information on the display comfortably, easily, accurately
and quickly (where necessary) — as when a paper “hardcopy” placed on the work desk is read.
One consideration is what can be called the positional sensitivity of the screen. If positioned poorly,
displays are susceptible to external light sources: these can be reflected back to the viewer and can
contribute to reduced legibility of the information on the screen. In more compelling environments,
these light sources can give rise to glare. They can come from either natural light from windows or
from artificial lighting systems such as overhead mounted luminaries in offices.
Given the size and dimensions of most displays, a display is typically oriented in a vertical rather than
horizontal position. This orientation and position of the information to be read is considerably different
than that when a book or paper placed on the desk is read. The line of sight from the eye to the visual
vi © ISO 2018 – All rights reserved

ISO 9241-306:2018(E)
task is raised up to 45°, giving rise to a quite different visual background, often with a varying luminous
background arising from walls and other objects in the environment. These factors can affect the
working posture of a user trying to compensate between the line of sight angle to the display needed to
be maintained and the distance to the visual task.
These, and other, considerations demonstrate that the positioning of a display is much more important
than the mere positioning of paper or other hardcopy reading materials. They give rise to the need to be
able to adjust the display for orientation and height and to have the flexibility to set up the workstation
equipment so that the needs of a specific user can be met. The combination of display, lighting
environment and workstation equipment are the basics for an ergonomically well-designed workplace.
Unlike most visual task materials, displays are intended to be used for several years. Many other kinds
of work materials are used only once or a few times, or are renewed or refreshed when visibility is too
low or possibly too uncertain (e.g. safety instructions or warnings), or else simply remain unchanged
over time.
The display assessment methods presented in this document do not, in most cases, require expensive
measuring equipment and can generally be carried out easily in a working field environment. In
conducting these assessments, it ought to be possible to determine whether a problem is related to:
a) the display itself (or the display in combination with the graphic adapter);
b) the application software; or
c) physical environmental conditions.
In cases involving the display, it is beneficial that the workstation set-up be reviewed to determine
whether it meets the supplier’s recommendations; if it does not, another assessment is performed
to determine how it can be made to meet them. In cases involving the application software, it can be
necessary to contact the software developers of the application product in order to ascertain possible
corrective action. In cases involving conditions in the physical environment, simple re-orientations or
the repositioning of the workstation and/or display can be a satisfactory solution; whereas, in more
complex situations, it can be necessary to make arrangements with the relevant interested parties in
order to ascertain appropriate actions and their feasibility. For details, see Annex B.
The ISO 9241 series was originally developed as a 17-part International Standard on the ergonomics
requirements for office work with visual display terminals. As part of the standards review process, a
major restructuring of the ISO 9241 series was agreed to broaden its scope, to incorporate other relevant
standards and to make it more usable. The general title of the revised ISO 9241 series, (Ergonomics of
human-system interaction) reflects these changes and aligns the series with the overall title and scope
of Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 4, Ergonomics of human-system
interaction. The revised series is structured as a series of standards numbered in the “hundreds”: the
100 series deals with software interfaces, the 200 series with human centred design, the 300 series
with visual displays, the 400 series with physical input devices and so on.
See Annex A for an overview of the entire ISO 9241 series.
INTERNATIONAL STANDARD ISO 9241-306:2018(E)
Ergonomics of human-system interaction —
Part 306:
Field assessment methods for electronic visual displays
1 Scope
This document establishes optical, geometrical and visual inspection methods for the assessment of a
display in various contexts of use according to ISO 9241-303.
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 9241-302, Ergonomics of human-system interaction — Part 302: Terminology for electronic visual
displays
ISO 9241-303:2011, Ergonomics of human-system interaction — Part 303: Requirements for electronic
visual displays
ISO 9241-307, Ergonomics of human-system interaction — Part 307: Analysis and compliance test methods
for electronic visual displays
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 9241-302 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
4 Preparation for assessment
4.1 Cleaning
Ensure that the visual display is clean; otherwise, clean it according to the manufacturer’s instructions.
4.2 Set-up
The visual display shall be physically prepared for assessment. Drive the visual display with the
following parameters:
— resolution: use the native resolution or the resolution recommended by the manufacturer;
— in case of CRT, see Annex E;
— image size: adjust to a specified size.
ISO 9241-306:2018(E)
NOTE Use the factory-recommended (physical) resolution. Changing this native resolution to another can
cause a degradation of the display image quality and character presentation, due to imperfect pixel interpolation
(see Figure 1).
a)  Physical b)  Reduced
Figure 1 — Comparison of letters displayed with physical and reduced resolutions
4.3 Display warm-up
Allow sufficient time (at least 20 min) for the display luminance to stabilize. When indicated by the
manufacturer, it shall be warmed up for the specified time.
NOTE For some technologies, a specific warm-up sequence is sometimes recommended. For example,
Electronic Paper Displays (EPD) can recommend that the test pattern be refreshed three times before taking
measurements.
4.4 Control settings of the visual display
The manufacturer should deliver the visual display with a factory setting that helps the user to use the
visual display in an ergonomic and efficient way within the intended context of use. If available, the
user should follow the recommendations given by the manufacturer for the setup conditions.
Addressed controls are the brightness control, the contrast control and the gamma adjustment.
For visual displays that permit grey scale rendering, use the output of the 16-step equally spaced grey
scale of test chart AE06 with samples between black and white, see Figure D.2.
In the intended environment, perform a visual check of the following display output properties:
1) The lowest two black levels should just be discriminated.
2) The lightest two white levels should just be discriminated.
3) All grey levels should be distinguishable.
4) The visual display should have an appropriate brightness level.
To achieve these conditions, apply the factory settings and recommendations of the display
manufacturer for the setup conditions. If available, use the controls of the visual display to meet the
above display output properties.
In a dark room, the 16-step grey scale should be approximately visually equally spaced, if the gamma
is adjusted according to IEC 61966-2-1. For any ergonomic output in a non-dark environment, it is
intended that the grey scale is approximately equally space. If this output setup stage is reached for
the dark environment, then the reflection of the ambient light on the display surface changes the visual
equal spacing. The changes increase with increasing ambient reflections on the screen. In the worst
case, about 5 dark grey steps may not be distinguishable.
2 © ISO 2018 – All rights reserved

ISO 9241-306:2018(E)
5 Assessment methods
5.1 Viewing conditions
5.1.1 Design viewing distance
The optimum distance between the visual display and the user's eyes depends on various factors,
in particular character legibility (see Table 1) and in certain cases the possibility of viewing a full
application without head movement (see Table 2). The design viewing distance, i.e. the distance
specified by the manufacturer of the display is set to >300 mm (see ISO 9241-303). The optimum
viewing distance for desktop office work in a seated position is about 600 mm. However, individual
users tend to prefer settings between 400 mm and 750 mm. Viewing distances in this range for most
people require character heights that subtend between 20′ to 22′ of arc (see ISO 9241-303).
Check whether the display is used within the specified viewing distance, D. Measure the distance from
the user's eyes to the centre of the screen with a ruler. For desktop office work, the normal range is
400 mm to 750 mm: if the chosen distance is outside of this range, verify that there is not an underlying
problem, such as bad image quality, incorrect font size or an uncorrected vision problem.
If the visual task requires that the entire application, i.e. its page or line width, is viewed at a glance, i.e.
without head movements, the minimum viewing distances from Table 2 are recommended. They result
from the maximum horizontal viewing angle of ±15° with respect to the normal on the screen surface,
which allows such viewing at a glance and depends on screen size. Typical applications are to be found
in control rooms. Figure 2 shows the relation between viewing angle, application width and viewing
distance.
Table 1 — Optimum and maximum viewing distances for character legibility
Character height Viewing distance of generally accepted legibility Maximum viewing distance
mm cm cm
1,4 — 30
2 33 43
3 49 65
4 66 86
4,6 75 99
9,2 150 197
18,3 300 394
NOTE 1  The maximum viewing distance is based on character height of 16′ of arc. Generally accepted legibility, i.e. one
that is well accepted by most users, is calculated based on 21′ of arc. The optimum character height for task performance
is a compromise between the legibility goal and the goal of “surveying at a glance” — presenting all information related to
the same context on the same screen.
NOTE 2  The simplified rule of thumb for character legibility is: for optimum legibility, viewing distance
≈165 × character height:
— acceptable range ≈ ±30 % for most users;
— acceptable range ≈ ±100 % for some users.
ISO 9241-306:2018(E)
Table 2 — The smallest viewing distance at which the full application width can be used
without need for head movement
Width of the application (or page or line) Minimum viewing distance in order to avoid head
movement
cm cm
16 30
21 40
30 56
40 75
50 94
60 112
150 280
300 560
NOTE 1  The relationship is based on the ±15° requirement illustrated by Figure 2.
NOTE 2  In the field, it can be convenient to use the following approximation as a rule of thumb: viewing distance
>1,9 × application width.
Key
1 screen width, W
2 viewing angle (±15°)
3 viewing distance, D
4 viewing location
Figure 2 — Viewing distance and viewing angle
5.1.2 Design viewing direction
If the display is a flat panel, check that it is used for the specified viewing direction class according to
ISO 9241-303 and ISO 9241-307.
4 © ISO 2018 – All rights reserved

ISO 9241-306:2018(E)
5.1.3 Gaze and head tilt angles
Verify that the work station and the visual display allow the user to view the screen with a gaze angle
from 0° to 45° and a head tilt angle from 0° to 20°, using a device for measuring angles such as protractor
or goniometer.
5.1.4 Virtual images
See ISO 9241-303:2011, Annex E.
5.2 Luminance
5.2.1 Illuminance
Measure the screen illuminance using a lux meter. Place the lux meter’s sensor directly in the centre of
the screen at the same tilt angle as applied by the user. Check that no shadows are falling onto the sensor.
Verify that the measured illuminance corresponds to the value specified by the supplier.
5.2.2 Display luminance
Measure the area luminance with a luminance meter in the centre of the visual display. Use:
a) full screen white at maximum grey level;
b) a white box at maximum grey level with a size of 4 % of the active display area, as per Formula (1).
A = H / 5 × W / 5 (1)
view view
where
A is the active display area;
H is the height of the active display area, measured in meters;
view
W is the width of the active display area, measured in meters.
view
Place the luminance meter perpendicular to the display surface on the target. Verify that the
measurement area of the luminance meter is smaller than the target.
Verify that the measured luminance values are in accordance with ISO 9241-307.
In case of interest, e.g. for determination of the lowest and highest luminance, repeat the measurement
in measurement locations as defined by ISO 9241-307 for the individual technology.
5.2.3 Luminance balance and glare
Measure the luminance of the display (e.g. full screen white), of a frequently viewed task area (e.g. a
document on the desk) and of a selected surround (e.g. a room wall). Calculate the luminance ratio
between the screen and the frequently viewed area. Perform the same calculation for the luminance
ratio between the screen and selected surround. Verify that the ratios are in accordance with the value
range specified in ISO 9241-303.
A possible method of controlling the avoidance of glare is to check whether the surface of the housing is
matte or glossy. Glossy surfaces can produce glare; the gloss value can be measured with a gloss meter
or gloss reference samples.
ISO 9241-306:2018(E)
5.2.4 Luminance adjustment
Verify that the luminance of the display and the contrast between characters and character background
on the display are adjustable by the user to the ambient environmental conditions of the workplace.
5.3 Special physical environments
5.3.1 Vibration
See ISO 9241-303:2011, 5.3.2.
5.3.2 Wind and rain
See ISO 9241-303:2011, 5.3.3.
5.3.3 Excessive temperatures
See ISO 9241-303:2011, 5.3.4.
5.4 Visual artefacts
5.4.1 Luminance non-uniformity
Estimate the luminance non-uniformity by sequentially viewing different areas on the screen to
determine the degree of non-uniformity. If it is determined that a noticeable amount of luminance non-
uniformity is present, then the measurement of luminance with a luminance meter is recommended.
The measurement locations are the positions on the screen with the lowest and highest luminance
(see 5.2.2). Determine the luminance non-uniform ratio using Formula (2):
 LL− 
maxmin
L = 100 % (2)
 
NU
L
max
 
where
L is the luminance non-uniformity;
NU
L is the lowest luminance in cd/m ;
min
L is the highest luminance in cd/m .
max
Verify that the luminance uniformity value is according to ISO 9241-307.
5.4.2 Colour non-uniformity
Display the full screen with only one colour and estimate the colour non-uniformity by sequentially
viewing different areas on the screen. Repeat with different colours.
The subjective impression of colour is not only determined by the colour itself (chromaticity) but also
by the luminance. For applications requiring exact colour distinction, use a colorimeter or a spectro-
photometer. For further details, see ISO 9241-305.
6 © ISO 2018 – All rights reserved

ISO 9241-306:2018(E)
5.4.3 Contrast non-uniformity
Calculate the contrast non-uniformity from the values measured in 5.2.2 using Formula (3):
 
CC−
maxmin
C = 100 % (3)
 
NU
C
max
 
where
C is the contrast non-uniformity;
NU
C is the lowest contrast;
min
C is the highest contrast.
max
5.4.4 Geometric distortions
Disturbing changes of character form or character location due to image stability or geometry faults
should not occur. Such geometrical faults can be ascertained, for example, by placing a rectangular
sheet of paper on the horizontal or vertical lines in the intended area of the display.
Most of these faults can be corrected using the screen display controls.
5.4.5 Pixel faults
5.4.5.1 Pixel/subpixel stuck on
These pixels/subpixels alw
...