EN ISO 13406-2:2001

SLOVENSKI STANDARD
01-september-2002
Ergonomske zahteve za delo s prikazovalnimi zasloni na osnovi ravnih ekranov -
2. del: Ergonomske zahteve za zaslone z ravnim ekranom (ISO 13406-2:2001)
Ergonomic requirements for work with visual displays based on flat panels - Part 2:
Ergonomic requirements for flat panel displays (ISO 13406-2:2001)
Ergonomische Anforderungen für Tätigkeiten an optischen Anzeigeeinheiten in
Flachbauweise - Teil 2: Ergonomische Anforderungen an Flachbildschirme (ISO 13406-
2:2001)
Exigences ergonomiques pour travail sur écrans de visualisation a panneau plat - Partie
2: Exigences ergonomiques des écrans a panneau plat (ISO 13406-2:2001)
Ta slovenski standard je istoveten z: EN ISO 13406-2:2001
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.

EUROPEAN STANDARD
EN ISO 13406-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2001
ICS 13.180; 35.180
English version
Ergonomic requirements for work with visual displays based on
flat panels - Part 2: Ergonomic requirements for flat panel
displays (ISO 13406-2:2001)
Exigences ergonomiques pour travail sur écrans de
visualisation à panneau plat - Partie 2: Exigences
ergonomiques des écrans à panneau plat (ISO 13406-
2:2001)
This European Standard was approved by CEN on 4 February 2001.
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 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 Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2001 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 13406-2:2001 E
worldwide for CEN national Members.

Foreword
The text of the International Standard ISO 13406-2:2001 has been prepared by Technical
Committee ISO/TC 159 "Ergonomics" 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 June 2002, and conflicting national
standards shall be withdrawn at the latest by June 2002.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy,
Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United
Kingdom.
Endorsement notice
The text of the International Standard ISO 13406-2:2001 was approved by CEN as a
European Standard without any modification.
NOTE: Normative references to International Standards are listed in annex ZA (normative).
Annex ZA (normative)
Normative references to international publications
with their relevant European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions
of any of these publications apply to this European Standard only when incorporated in it by
amendment or revision. For undated references the latest edition of the publication referred to
applies (including amendments).
NOTE Where an International Publication has been modified by common modifications,
indicated by (mod.), the relevant EN/HD applies.
Publication Year Title EN Year
ISO 9241-3 1992 Ergonomic requirements for office EN 29241-3 1993
work with visual display terminals
(VDTs) - Part 3: Visual display
requirements
ISO 9241-6 1999 Ergonomic requirements for office EN ISO 9241-6 1999
work with visual display terminals
(VDTs) - Part 6: Guidance on the
work environment
ISO 9241-7 1998 Ergonomic requirements for office EN ISO 9241-7 1998
work with visual display terminals
(VDTs) - Part 7: Requirements for
display with reflections
ISO 9241-8 1997 Ergonomic requirements for office EN ISO 9241-8 1997
work with visual display terminals
(VDTs) - Part 8: Requirements for
displayed colours
INTERNATIONAL ISO
STANDARD 13406-2
First edition
2001-12-01
Ergonomic requirements for work with
visual displays based on flat panels —
Part 2:
Ergonomic requirements for flat panel
displays
Exigences ergonomiques pour travail sur écrans de visualisation
à panneau plat —
Partie 2: Exigences ergonomiques des écrans à panneau plat

Reference number
ISO 13406-2:2001(E)
©
ISO 2001
ISO 13406-2:2001(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not
be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this
file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this
area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2001
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body
in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.ch
Web www.iso.ch
Printed in Switzerland
ii © ISO 2001 – All rights reserved

ISO 13406-2:2001(E)
Contents Page
Foreword.v
Introduction.vi
1 Scope.1
2 Normative references.2
3 Definitions.2
3.1 Photometry.2
3.2 Colorimetry.4
3.3 Geometry.7
3.4 Display technology.10
3.5 Alphanumeric symbols.15
4 Symbols.17
5 Guiding principles.22
6 Performance requirements.23
7 Design requirements and recommendations .23
7.1 Design viewing distance.23
7.2 Design viewing direction .24
7.3 Design screen illuminance .28
7.4 Gaze and head-tilt angles .28
7.5 Chromaticity uniformity difference (See Figure 15).28
7.6 Character height.29
7.7 Stroke width.30
7.8 Character width-to-height ratio .30
7.9 Fill factor.30
7.10 Character format.31
7.11 Between-character spacing.31
7.12 Between-word spacing.31
7.13 Between-line spacing.31
7.14 Display luminance.32
7.15 Contrast (See Figure 19).33
7.16 Luminance balance.34
7.17 Reflections (See Figure 21) .34
7.18 Image polarity.37
7.19 Luminance uniformity (See Figure 24 and Table 14).37
7.20 Pixel faults.38
7.21 Image formation time .38
7.22 Absolute luminance coding.39
7.23 Blink coding.39
7.24 Temporal instability (flicker).39
7.25 Default colour set.39
7.26 Multicolour object size.39
7.27 Colour differences.40
7.28 Spectrally extreme colours.40
7.29 Number of colours.41
8 Measurements.41
8.1 Introduction.41
8.2 Supplier requirements.42
8.3 Test laboratory requirements.45
8.4 Test geometry.56
ISO 13406-2:2001(E)
8.5 Combined measurement for character design analysis.65
8.6 Combined measurement for luminance, contrast and diffuse illumination .66
8.7 Requirement evaluations.69
9 Compliance.109
Annex A (informative) Colour difference calculation .111
Annex B (informative) Flicker determination.114
Annex C (informative) Bidirectional Reflectance Distribution Function (BRDF).123
Bibliography .140

iv © ISO 2001 – All rights reserved

ISO 13406-2:2001(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this part of ISO 13406 may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 13406-2 was prepared by Technical Committee ISO/TC 159, Ergonomics,
Subcommittee SC 4, Ergonomics of human-system interaction.
ISO 13406 consists of the following parts, under the general title Ergonomic requirements for work with visual
displays based on flat panels:
— Part 1: Introduction
— Part 2: Ergonomic requirements for flat panel displays
Annexes A, B and C of this part of ISO 13406 are for information only.
ISO 13406-2:2001(E)
Introduction
ISO 13406 extends its companion standard ISO 9241 to account for the significant differences in ergonomic trade
offs present when flat panels are used.
The rationale for this part of ISO 13406 is presented in ISO 13406-1.
This part of ISO 13406 presents the requirements for visual display units (VDUs) based on flat panels as defined in
ISO 13406-1. It is intended for evaluators and users of this technology. Some document users will find part of the
material complex. Notes, figures and examples are provided to lessen the problem. The legibility of flat panels is a
principal concern. The requirements are primarily based on the visual ergonomic research used in ISO 9241-3 and
on new research referenced in this part of ISO 13406. Here, as in ISO 9241-3, some requirements are based on
visual comfort, muscular comfort and user acceptability. This part of ISO 13406 includes requirements and
recommendations that are based on legibility, comfort and acceptability that arise when multicolour displays are
used, based on the visual ergonomic research described in ISO 9241-8, but modified and extended to consider the
unique trade offs of flat panels. Legibility in the presence of ambient room light and the acceptability of unwanted
reflected images are addressed covering the flat panel aspects covered in ISO 9241-7 for cathode ray tube (CRT)
technology.
Clause 3 Definitions presents or recalls those terms needed to specify requirements and measurements. Where
possible, definitions taken from other publications are quoted verbatim. If some change has been made, the
definition is followed by a note stating “Adopted from ISO xxxx:date,x.x”. Since this part of ISO 13406 often relies
on mathematical models and physical measurements to ensure the fitness of purpose of flat panel VDUs, a
clause 8 (Symbols) is presented as a convenient reference.
Guiding principles and performance requirements’ clauses modelled on ISO 9241-3 are presented to remind
document users of the foundations of the work.
Design requirements and recommendations present the physical attributes that are to be strictly followed to
conform (indicated by the word: shall) or preferred but not necessarily required (indicated by the word: should). The
topics of design viewing distance, design viewing direction and design screen illumination depart somewhat from
the precedents of ISO 9241-3. Two reasons exist:
a) an important type of flat panel has viewing characteristics that require more careful control and consideration
of viewing direction than considered in ISO 9241-3;
b) there is no basis to assume that a flat panel VDU is tabletop mounted. These topics are presented as
ergonomically constrained, supplier-specifications. This is not unprecedented, viewing distance was handled
this way in ISO 9241-3. Once specified, these requirements become the conditions under which all other
attributes are to be measured or decided.
A departure from ISO 9241-3 is the use of area-luminance. For CRT technology, the addressed locations are
generally close together so that a high-low-high-low-high-low-pixel pattern will exhibit less contrast than a sparse
pattern. Since the flat-panel pixel area is less than 100 % optically modulated (the fill factor is less than 1), the
difference between sparse and dense pattern contrast is minor. The luminance determination has to be
complicated by the need for viewing direction precision. The use of area-luminance simplification offsets that
somewhat.
Some requirements are presented in categories. For example, some flat panels exhibit long image-formation times.
For static images, such panels are ergonomically acceptable without reservation. Not all modern applications rely
solely on such static images. Requirement categories are therefore established. If the supplied equipment has such
a limitation, the supplier/evaluator is required to identify it. The system integrator, purchaser or user then can
consider whether the category is consistent with intended applications.
vi © ISO 2001 – All rights reserved

ISO 13406-2:2001(E)
Clause 8 covering measurements is intended for evaluators of flat panel VDUs. The panel surface is sampled for
evaluation. Three evaluation sites are chosen and measured, and compliance decisions can be made from these
measurements. Panels with large requirement margins do not require precision-evaluation equipment but panels
with small margins can.
Clause 9 covering compliance is closely modelled on ISO 9241-3. The alternative test (Visual performance and
comfort test) prepared as a normative annex in an amendment to ISO 9241-3, is cited as an alternative compliance
route.
Annex A provides additional information on colour difference. Annex B extends the analytic flicker determination
method of ISO 9241-3 to luminance-time modulation that is not CRT-like. Annex C informs the users of this
International Standard of new work on an alternate modelling method for screens with reflection properties that
cannot be adequately modelled with a simple combination of luminance coefficient (diffuse reflection) and
luminance factor (specular or regular reflection) and standardized assumptions about the environment. This
method develops the bidirectional reflection distribution function. When this work progresses further, it can possibly
become a normative method and replace the method in clause 8. The bibliography cites references.
INTERNATIONAL STANDARD ISO 13406-2:2001(E)

Ergonomic requirements for work with visual displays based
on flat panels —
Part 2:
Ergonomic requirements for flat panel displays
1 Scope
This part of ISO 13406
 establishes ergonomic image-quality requirements for the design and evaluation of flat panel displays,
 defines terms needed to address image quality on flat panel displays,
 specifies methods of determining image quality on flat panel displays, and
 establishes ergonomic principles for guiding these requirements.
This part of ISO 13406 is applicable to
 flat panel display screens when used to perform office tasks,
 flat panel display screens that consist of a regular array of picture elements arranged in evenly spaced rows
without built-in gaps,
 the presentation of fonts based on Latin-, Cyrillic- and Greek-origin alphabetic characters and Arabic numerals
on flat panel display screens,
 the presentation of Asian characters, and
 flat panel display screens that are large enough to display at least 40 Latin-origin characters.
This part of ISO 13406 is not applicable to
 flat panel technology applied to a display that uses optics to form an image that is not the same size as the
electro-optical transducer (projection applications of flat panel displays), or
 flat panel technology applied to a display limited to fixed-messages or segmented alphanumerics.
[See 2.13 IEC SC 47C (Central Office) 3:1992].
NOTE Some of the measurement methods (e.g. contrast and luminance) in this part of ISO 13406 are not applicable for
reflective flat panels. When technology has developed, appropriate measurement methods will be added to this part of
ISO 13406.
ISO 13406-2:2001(E)
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this part of ISO 13406. For dated references, subsequent amendments to, or revisions of, any of these publications
do not apply. However, parties to agreements based on this part of ISO 13406 are encouraged to investigate the
possibility of applying the most recent editions of the normative documents indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain
registers of currently valid International Standards.
CIE Publication No. 15.2:1986, Colorimetry. (Central Bureau of the Commission International d'Éclairage CIE),
Vienna, Austria.
ISO 9241-3:1992, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 3: Visual
display requirements.
ISO 9241-6, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 6: Guidance on
the work environment.
ISO 9241-7, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 7: Requirements
for display with reflections.
ISO 9241-8:1997, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 8:
Requirements for displayed colours.
3 Definitions
For the purposes of this part of ISO 13406, the following definitions apply.
NOTE The symbols used in certain definitions are explained in clause 4.
3.1 Photometry
3.1.1
area-luminance
luminance of an area of the screen that has a diameter of at least 10 pixels, such that the state of an individual
pixel has less than 2 % effect
NOTE Area-luminance is expressed in candelas per square metre (cd/m ).
3.1.2
background luminance
luminance of an area of the screen with no graphic images present
NOTE Background luminance is expressed in candelas per square metre (cd/m ).
3.1.3
contrast
〈in a perceptual sense〉 assessment of the difference in appearance of two or more parts of a field seen
simultaneously or successively (hence: brightness contrast, lightness contrast, colour contrast, etc.)
NOTE Adapted from IEC 60050 (845-02-47):1987.
3.1.4
EUT
Equipment Under Test
2 © ISO 2001 – All rights reserved

ISO 13406-2:2001(E)
3.1.5
Lambert's (cosine) law
for a surface element whose radiance or luminance is the same in all directions of the hemisphere above the
surface:
I(θ ) = I cos(θ ) (1)
n
Where I(θ ) and I are the radiant or luminous intensities of the surface element in a direction at an angle θ from the
n
normal to the surface and in the direction of that normal, respectively
[IEC 60050 (845-04-56):1987]
3.1.6
Lambertian surface
ideal surface for which the radiation coming from that surface is distributed angularly according to Lambert's cosine
law
[IEC 60050 (845-04-57):1987]
For an ideal diffuse reflectance standard:
r =p◊ q (2)
STD
STD
3.1.7
luminance contrast
ratio between the higher, L and lower, L , luminances that define the feature to be detected, measured by contrast
H L
modulation (C ) defined as:
m
L - L
HL
= (3)
C
m
L + L
HL
or contrast ratio (CR), defined as:
L
H
CR = (4)
L
L
NOTE 1 For flat panels, area-luminance targets can be used to approximate the luminances that define the feature to be
detected because pixels are discrete.
NOTE 2 Adapted from ISO 9241-3:1992, 2.22.
3.1.8
luminance coefficient (at a surface element, in a given direction, under specified conditions of illumination)
q , q
ν
quotient of the luminance of the surface element in the given direction by the illuminance of the medium
NOTE 1 The luminance coefficient is expressed in reciprocal steradians.
NOTE 2 Adapted from IEC 60050 (845-04-71):1987.
L
q = (5)
E
ISO 13406-2:2001(E)
3.1.9
luminance factor (at a surface element of a non-self-radiating medium, in a given direction, under specified
conditions of illumination)
β , β
ν
ratio of the luminance of the surface element in the given direction to that of a perfect reflecting or transmitting
diffuser identically illuminated
L
sample
b = (6)
L
perfect diffuser
NOTE 1 The luminance factor is expressed as unit: 1
NOTE 2 Adapted from IEC 60050 (845-04-69):1987.
3.1.10
optically anisotropic surface
optical surface for which the radiation deviates from that of a Lambertian surface by more than 10 % at any
inclination angle, θ < 45°
3.2 Colorimetry
3.2.1
CIE 1976 L*u*v* colour space
CIELUV colour space
three-dimensional, approximately uniform colour space produced by plotting in rectangular coordinates L*, u*, v*
quantities defined by the three equations:
¸
*
Ô
LY=-116 ( /Y ) 16, whenY /Y> 0,008 856
nn
Ô
*
Ô
LY= 903,3( /Y ), whenY /Y u 0,008 856
nn
(7)
˝
**
Ô
uL=-13 (u¢¢u )
n
Ô
**
Ô
vL=-13 (v¢¢v )
n ˛
Y, u', v' describe the colour stimulus considered and Y , u' , v' describe a specified white achromatic stimulus.
n n n
NOTE Approximate correlates of lightness, saturation, chroma and hue may be calculated as follows:
È ˘
CIE 1976 u, v saturation=-13 uu¢¢+vv¢-¢ (8)
s () ( )
uv n n
Í ˙
Î ˚
* *
CIE 1976 u, v chroma ==** (9)
Cs
+ L
uv uv
uv

*
ʈ
ʈ
vv¢¢- v
n
h==arctan arctan , such that
uv Á˜
Á˜
*
˯uu¢¢-
n ˯u
0∞uW hi<90∞,fv** W0and 0u
uv
CIE 1976 u, v hue-angle 90∞uW hi<180∞,fv** 0and 0u < (10)
uv
180∞u hi<270∞,fv**<<0and 0u
uv
270∞uW hi<360∞,fv**<0and 0u
uv
[IEC 60050 (845-03-54)]
4 © ISO 2001 – All rights reserved

ISO 13406-2:2001(E)
3.2.2
CIE 1976 uniform-chromaticity scale diagram
CIE 1976 UCS diagram
uniform-chromaticity-scale diagram produced by plotting in rectangular coordinates v¢ against u¢, quantities
defined by the equations (11):
44Xx
u¢==
XY++15 3Z -2x+12y+ 3
(11)
99Yy
v¢==
XY++15 3Z -2x+ 12y+ 3
See Figure 1 and IEC 60050 (845-03-53).

NOTE The curve annotations are wavelengths in nanometers.
Figure 1 — CIE 1976 UCS Diagram

3.2.3
CIE 1976 L*u*v* colour difference
CIELUV colour difference
difference between two colour stimuli, defined as the Euclidean distance between the points representing them in
the L*u*v* space and calculated as equation:
22 2
È ˘ 2
** * *
DDEL=+Du+Dv (12)
() ( ) ( )
uv Í ˙
Î ˚
The set X Y Z and corresponding uv¢¢ define the colour of the nominally white object-colour stimulus.
n n n
nn
(See CIE Publication No. 15.2.)
[IEC 60050 (845-03-55)]
ISO 13406-2:2001(E)
3.2.4
chromaticity uniformity difference
distance on the CIE 1976 UCS diagram
Duv¢¢=-()u¢ u¢ + (v¢-v¢ )  (13)
12 1 2
where
are the coordinates of the same colour displayed at sites 1 and 2.
uv¢¢, and u¢ ,v¢
11 2 2
NOTE This is the appropriate measure of colour uniformity if luminance is not uniform or if the objects are not adjacent.
(See 3.2.2.)
3.2.5
dominant wavelength of a colour stimulus, λ
d
wavelength of the monochromatic stimulus that, when additively mixed in suitable proportions with the specified
achromatic stimulus, matches the colour stimulus considered
NOTE In the case of purple stimuli, the dominant wavelength is replaced by the complementary wavelength. See
IEC 60050 (845-03-44).
3.2.6
same dominant wavelength
two colours have the same dominant wavelength if the difference between the hue angles of each colour is small
3.2.7
spectrally extreme colours
spectrally extreme colours are extreme blue and extreme red
′ ′
NOTE Extreme blue is any colour with v < 0,2. Extreme red is any colour with u > 0,4. The extreme regions are illustrated
in Figure 2.
NOTE The curve annotations are wavelengths in nanometers.
Figure 2 — Extreme red and extreme blue
6 © ISO 2001 – All rights reserved

ISO 13406-2:2001(E)
3.2.8
uniform colour space
colour space in which equal distances are intended to represent a threshold or suprathreshold perceived colour
differences of equal size
[IEC 60050 (845-03-51):1987]
3.2.9
uniform-chromaticity-scale diagram
UCS diagram
two-dimensional diagram in which the coordinates are defined with the intention of making equal distances
represent as nearly as possible equal steps of colour discrimination for colour stimuli of the same luminance
throughout the diagram
[IEC 60050 (845-03-52):1987]
3.3 Geometry
3.3.1
active area
part of a display screen area delimited by picture elements [2.1, IEC SC 47C(Central Office) 3]
3.3.2
angular subtence
size of a visual target at a specified viewing distance, e.g. at the design viewing distance
ʈtarget height
Angular subtence in degrees = 2 arctan (14)
Á˜
˯2 ¥viewing distance
ʈ
target height
Angular subtence in minutes of arc = 60 ¥ 2 arctan
Á˜
˯2 ¥viewing distance
(15)
3 438 × target height
ª
viewing distance
NOTE The dimension for angular subtence is degrees (°), which is further divided into minutes of arc (′) and seconds of arc
(″).
3.3.3
anisotropic display
display (usually a liquid crystal display) with emitted luminance and/or luminance coefficient that meets the criterion
in 3.1.10
3.3.4
coordinate system
a normal spherical coordinate system (r, q, f)
See Figure 3.
ISO 13406-2:2001(E)
Key
E Position of the entrance pupil of the luminance meter
OE = r Working distance
1 f = 0° (3 o’clock)
NOTE 1 In some literature, the azimuth is specified by clock positions. 3 o’clock is defined as φ = 0°.
NOTE 2 Normally only positive values for θ are used. (-θ, φ) is identical to the direction (+θ , φ ± 180°).
Figure 3 — Coordinate system
NOTE 1 The following is a detailed definition of the coordinate system. See Figure 4.
Let a point (pixel or centre of a visual target) be labelled O. Construct a line, from O to the entrance pupil of the
measuring instrument, OE, and a line, ON normal to the image plane of the display. The angle from ON to OE in
the ON - OE plane is the inclination angle, θ. The distance OE is the radius r.
Let P be any point on the line that is formed by the projection of OE on the image plane. Construct a line, OX in
that plane to the right of and parallel to the line that bisects the active area horizontally. This is the X axis. The
azimuth angle, φ, is the counterclockwise angle between OX and OP.

Key
1 3 o’clock; right edge of the screen as seen from the user
2 12 o’clock; top edge of the screen as seen from the user
3 6 o’clock; bottom edge of the screen as seen from the user
4 Image surface of the screen
Figure 4 — Coordinate system - definition
8 © ISO 2001 – All rights reserved

ISO 13406-2:2001(E)
NOTE 2 For more information on coordinates and viewing angles, see VESA Flat Panel Display Measurements Standards
(1998), chapter 300-2.
3.3.5
Frankfort plane
is an imaginary plane through the head established by the lateral extensions of a line between the tragion and the
lowest point of the orbit
See Figure 5.
Key
1 Tragion
2 Frankfort plane
3 Inferior ridge of the orbit
Orbit is the cavity in the skull that contains the eye. Tragion (or tragus) is the projection of cartilage in the pinna of
the outer ear that extends back over the opening of the external auditory meatus.
Figure 5 — Frankfort plane
3.3.6
gaze angle
angle from the Frankfort plane to the plane formed by the pupils and the visual target
See Figure 6.
Key
1 Gaze angle
2 Line of sight
Figure 6 — Gaze angle
NOTE The comfortable range is about 0° to about 45°.
3.3.7
head tilt angle
angle from the Frankfort plane to the horizontal plane and due to tilt of the head
NOTE When the head is erect, the head tilt angle is about 4°
See Figure 7.
ISO 13406-2:2001(E)
Key
1 Horizontal plane
2 Head tilt angle
Figure 7 — Head tilt angle
NOTE The comfortable range is about 0° to about 20°.
3.3.8
viewing angle range
conical space originating at a pixel that includes all viewing directions for which specifications are satisfied
[IEC SC 47C (Central Office) 3]
3.4 Display technology
3.4.1
fill factor
fraction (of the total area geometrically available to a pixel) that can be altered to display information
[ISO 9241-3:1992, 2.15]
3.4.2
emissive display
display that contains its own source(s) of light
NOTE 1 This light can be produced by the transducer itself or provided by one or more internal light source(s) modulated by
the transducer.
NOTE 2 Adapted from 2.4, IEC/SC 47C (Central Office) 3.
3.4.3
gray scale
a display is said to have gray scale if it can display images demanding more than two luminance levels
[2.4, IEC/SC 47C (Central Office) 3]
3.4.4
image formation time
time for the relative luminance of a visual object to change from 0,1 to 0,9
NOTE 1 The relative luminance is
(L – L )/(L – L );
MAX MAX MIN
where
L and L are the time averaged highest and lowest luminance states, respectively;
MAX MIN
L is the instantaneous luminance.
NOTE 2 The relative luminance is filtered to eliminate temporal variations that are not visually detectable. Image formation
time is resolved to the ranges shown in Table 1 and is expressed in milliseconds.
10 © ISO 2001 – All rights reserved

ISO 13406-2:2001(E)
NOTE 1 This illustrates a typical case.
NOTE 2 A constant-luminance back light is assumed (after prefiltering for 4kS/s sampling).
NOTE 3 Figure 8 illustrates the image formation time. The trace with the marks represents the unfiltered luminance time,
normalized to a range of 1,0. The bold trace is the first trace filtered to include those frequencies that are psychophysically
significant. The image formation time is judged on this trace. In this example, t = 2,00 ms is the time recorded at 0,1 of the
maximum luminance with the luminance increasing; t = 15,25 ms is the time recorded at 0,9 of the maximum luminance with
the contrast increasing; t = 50,00 ms, is the time recorded at 0,9 of the maximum luminance with the luminance decreasing;
and, t = 61,75 ms is the time recorded at 0,1 of the maximum luminance with the luminance decreasing. Image formation time
is t – t + (t – t ) = 25 ms. The luminance time is sampled at 4 kS/s, so the precision is ± 0,5 ms.

2 1 4 3
NOTE 4 For flat panel displays with very fast electro-optic physics, the refresh period is the image formation time.
Figure 8 — Image formation time
Table 1 — Image formation time in milliseconds
Time range Significance
t u 10 Motion artefacts become undetectable at image formation times less than 3 ms.
10 < t u 55 Contrast is stable for most applications. Motion artefacts can be distracting.
55 < t u 200 Applications using scrolling, animation and pointing devices lose detectable
contrast. Blink coding from 0,33 Hz to 5 Hz is operable.
t > 200
Noticeable loss of contrast observed during key entry, scrolling, animation, and
blink coding. Pointing devices with rapid cursor positioning can be used only with
special techniques.
3.4.5
absolute luminance coding
information presented where the only dimension that is used for visual differentiation is difference in image
luminances
ISO 13406-2:2001(E)
3.4.6
relative luminance coding
information presented where either the coded images are touching or the luminance difference is secondary to a
primary differentiation such as shape or colour
3.4.7
pixel
smallest element that is capable of generating the full functionality of the display
3.4.8
pixel pitch
the distance between corresponding points on adjacent pixels, both horizontally (H ) and vertically (V )
pitch pitch
NOTE Pixel pitch is expressed in millimetres.
3.4.9
reflective display
display device that modulates light from an external source by reflection
[2.12, IEC 47 CO 2]
3.4.10
screen tilt angle
α
angle formed by the intersection of the plane tangent to the centre of the display and the horizontal plane
NOTE Screen tilt angle is expressed in degrees.
See Figure 9.
Key
1 Viewing side
2 Display
3 Horizontal surface (e.g. a table)
Figure 9 — Screen tilt angle, α
NOTE a is identical to the angle, A in 6.1.2 of ISO 9241-3:1992.
3.4.11
small-size panel
a flat panel with a viewing area with the smallest dimension in the range of 1,6° to 4,8° at the design viewing
distance and with the largest dimension of at least 4,8° at the design viewing distance
See Figure 10.
12 © ISO 2001 – All rights reserved

ISO 13406-2:2001(E)
Key
1 Design viewing distance
Figure 10 — Small-size panel
NOTE 1 Smaller panels will not hold more than 40 complying Latin characters and are outside the scope of the standard. The
definition is used in screening and selecting measurement locations only. See 8.4.2 Standard measurement locations.
NOTE 2 For a viewing distance of 500 mm, 1,6° = 14 mm; 4,8° = 42 mm.
3.4.12
subpixel
a separately addressed internal structure in a pixel that extends the pixel function
NOTE Examples include primary colour subpixels used in some multicolour flat panels and multiple-size subpixels, used to
create half-tone-like gray scale effects. Microstructure within primary subpixels is sometimes used to minimize anisotropy or to
minimize fault visibility by adding redundancy in flat panels. Such microstructures are still called subpixels in this part of
ISO 13406. Display engineering literature often uses the term “dot” which is not used in this part of ISO 13406.
3.4.13
pixel faults
local defects of types 1, 2 or 3
See Tables 2 and 3.
ISO 13406-2:2001(E)
Table 2 — Pixel faults
Fault type Description
Type 1 fault Pixel in stuck high state
(when system command = minimum luminance) (L > 0,7
...