ISO 24505-1:2025
(Main)Ergonomics — Accessible design — Part 1: Colour combinations for young and older people without visual impairments
Ergonomics — Accessible design — Part 1: Colour combinations for young and older people without visual impairments
This document provides a method for creating conspicuous colour combinations for use in visual signs and displays, taking into account viewer age. It is based on the perceived similarity of colours at photopic and mesopic lighting conditions. This document applies to the design of visual signs and displays in which multiple colours are used so that the colours are conspicuous to people of any age, including older people who do not have deficient colour vision. The method and data in this document are not applicable to the design of visual signs and displays for people with colour deficiencies or medical disorders affecting vision. This document applies to the reflective or object mode colours but may apply to self-luminous mode colours if the colour coordinates are appropriately transferred to those of the object mode colours.
Ergonomie — Conception accessible — Partie 1: Combinaisons de couleurs pour les jeunes et les personnes plus âgées sans déficience visuelle
L'ISO 24505 :2016 fournit une méthode pour la création de combinaisons de couleurs perceptibles destinées à être utilisées sur les panneaux de signalisation et les affichages tenant compte de l'âge de l'observateur. Elle est basée sur la similitude perçue des couleurs dans les conditions d'éclairage photopiques et mésopiques. L'ISO 24505 :2016 s'applique à la conception des panneaux de signalisation et des affichages dans lesquels plusieurs couleurs sont utilisées de sorte que ces couleurs soient perceptibles par des personnes de tous âges, y compris les personnes âgées ne présentant pas de déficience de la vision des couleurs. La méthode et les données de l'ISO 24505 :2016 ne sont pas applicables à la conception des panneaux de signalisation et des affichages pour les personnes présentant une déficience de la vision des couleurs ou des troubles médicaux affectant la vision. L'ISO 24505 :2016 s'applique en principe aux couleurs en mode réfléchissant ou objet, mais peut s'appliquer aux couleurs en mode auto-luminescent si les coordonnées chromatiques sont transposées de manière appropriée en celles des couleurs en mode objet.
General Information
Relations
Standards Content (Sample)
International
Standard
ISO 24505-1
First edition
Ergonomics — Accessible design —
2025-09
Part 1:
Colour combinations for young
and older people without visual
impairments
Ergonomie — Conception accessible —
Partie 1: Combinaisons de couleurs pour les jeunes et les
personnes plus âgées sans déficience visuelle
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Factors affecting conspicuity of colour combinations . 2
4.1 General .2
4.2 Luminance level .2
4.3 Ageing effect .3
4.4 Viewing mode and condition .3
5 Colour combinations using fundamental colours and their conspicuity . 3
5.1 Fundamental colours and their combinations .3
5.2 Classification of the conspicuity of colour combinations .4
5.3 Tables of two-colour combinations of fundamental colours and their conspicuity .5
5.4 Span 1 of fundamental colours . .7
6 Procedures to create a colour combination . 8
Annex A (normative) Spans of fundamental colours (Span 2) .18
Annex B (informative) Colouring example: A train network .31
Annex C (informative) Guidance for transformation of Munsell colour system to CIE XYZ system
and to sRGB system in monitor displays .33
Bibliography .34
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
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with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had notreceived notice of (a)
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This document was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 5,
Ergonomics of the physical environment.
This first edition of ISO 24505-1, together with ISO 24505-2, and ISO 24505-3, cancels and replaces
ISO 24505:2016, of which it constitutes a minor revision. The change is as follows:
— minor editorial changes.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
While the social care of older people has widely spread in many countries, the design and production of
visual signs and displays do not always take into account the unique needs of older people. This document
presents a method for assessing and designing signs and displays in our visual environment so that they are
clearly visible to older people. This document includes a method and data for creating conspicuous colour
combinations in visual signs and displays seen by people at any age by considering age-related change of
human colour vision.
A reasonably large number of people, especially men, have defective colour vision of various types, and
some smaller part of the population have suffered from medical disorders of the eye such as low vision. This
document is not applicable to colour combinations for people who have deficient colour vision or medical
disorders affecting vision. Other International Standards provide methods to enable the creation of colour
combinations for people with widely varying visual disabilities, including those for people with normal
colour vision at any age, people with colour deficiencies and people with low vision, and for general guidance
on the use of the colour-combination standard.
In describing colours in this document, the Munsell colour system is used, which is a colour-order system
recommended by the Commission Internationale de l’Eclairage.[9]
This document adopts the principles of accessible design given in Reference [3] and amplified in Reference [4].
v
International Standard ISO 24505-1:2025(en)
Ergonomics — Accessible design —
Part 1:
Colour combinations for young and older people without
visual impairments
1 Scope
This document provides a method for creating conspicuous colour combinations for use in visual signs and
displays, taking into account viewer age. It is based on the perceived similarity of colours at photopic and
mesopic lighting conditions.
This document applies to the design of visual signs and displays in which multiple colours are used so that
the colours are conspicuous to people of any age, including older people who do not have deficient colour
vision. The method and data in this document are not applicable to the design of visual signs and displays for
people with colour deficiencies or medical disorders affecting vision.
This document applies to the reflective or object mode colours but may apply to self-luminous mode colours
if the colour coordinates are appropriately transferred to those of the object mode colours.
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 3864-1, Graphical symbols — Safety colours and safety signs — Part 1: Design principles for safety signs and
safety markings
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology 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
colour similarity
extent to which some percentage of the population judge a given colour as similar to a fundamental
reference colour
EXAMPLE Colour similarity of 50 % means that half of the people judge a given colour as similar to the
reference colour.
3.2
fundamental colour
set of basic colours perceived by people with normal colour vision, which are red, orange (yellow-red),
yellow, green-yellow, green, blue-green, blue, purple-blue, purple, red-purple, black, grey, and white, in
accordance with the Munsell colour system
3.3
mesopic vision
vision by the normal eye intermediate between photopic and scotopic vision
Note 1 to entry: In mesopic vision, both the cones and the rods are active.
[SOURCE: CIE S 017/E:2020, modified — Note 1 to entry added.]
3.4
photopic vision
vision by the normal eye in which cones are the principle active photoreceptors
Note 1 to entry: Photopic vision normally occurs when the eye is adapted to levels of luminance of at least 5 cd/m .
Note 2 to entry: Colour perception is typical of photopic vision.
[SOURCE: CIE S 017/E:2020, modified — Notes to entry added.]
3.5
scotopic vision
vision by the normal eye in which rods are the principle active photoreceptors
−3 2
Note 1 to entry: Scotopic vision normally occurs when the eye is adapted to levels of luminance of less than 10 cd/m .
Note 2 to entry: In comparison with photopic vision, scotopic vision is characterized by the lack of colour perception
and a shift of visual sensitivity towards shorter wavelengths.
[SOURCE: CIE S 017/E:2020, modified — Notes to entry added.]
3.6
span
area in a colour space in which colours are perceived as similar to a reference
colour in colour appearance
Note 1 to entry: The span is definable differently according to the extent of similarity to the reference fundamental
colour, such as “very similar”, “moderately similar”, or “slightly similar”.
Note 2 to entry: The Munsell colour system is used to describe the span in this International Standard.
4 Factors affecting conspicuity of colour combinations
4.1 General
Colour combinations should be conspicuous whenever colours are used for identifying, discriminating,
or recognizing information in visual signs and displays. The factors given in 4.2. to 4.4 shall be taken into
account in creating and using colour combinations.
For the special use of colour for safety, the selection of colours and colour combinations shall conform to
ISO 3864-1.
NOTE "Conspicuity" of a colour combination is the distinctiveness between, and identification of, each colour
used in the combination. In colour science, "conspicuous colour combination" applies to a combination with relatively
large colour differences, whereas "colour discrimination" refers to small colour differences such as a just noticeable
difference.
4.2 Luminance level
Colour appearance changes with luminance level. This effect shall be taken into consideration, particularly
in choosing colours for use in low-luminance environments such as those in mesopic vision.
EXAMPLE In mesopic vision, reddish colours appear relatively darker and bluish colours appear brighter.
4.3 A
...
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