SIST EN ISO 9241-391:2016

Ergonomics of human-system interaction - Part 391: Requirements, analysis and compliance test methods for the reduction of photosensitive seizures (ISO 9241-391:2016)

ISO 9241-391:2016 provides requirements and recommendations for reducing photosensitive seizures (PSS), while viewing images on electronic displays.
The requirements and recommendations in this part of ISO 9241 are designed to be applied to image contents. By image contents, reference is made to the images independent of the device or environment in which they are displayed.
The requirements and recommendations in this part of ISO 9241 are for the protection of the vulnerable individuals in the viewing population who are photosensitive and who are therefore liable to seizures triggered by flashing lights and regular patterns, including certain repetitive images.
NOTE 1       ITU considers the image safety issues in relation to broadcasting. Some of these are described in ITU-R BT.1702.[2]
NOTE 2       There are some related recommendations in ISO/IEC 40500:2012, W3C Web Content Accessibility Guidelines (WCAG) 2.0, for web contents accessibility.
NOTE 3       Photosensitive seizures and photosensitive epilepsy, that is, chronic conditions characterized by those repeated seizures are medical conditions. Clinical aspects of photosensitivity appear in Annex C. Visually induced seizures are equivalent to PSS.

Ergonomie der Mensch-System-Interaktion - Teil 391: Anforderungen, Analysen und Prüfverfahren zur Konformität zur Verringerung epileptischer Anfälle ausgelöst durch photosensitive Reize (ISO 9241-391:2016)

Dieser Teil von ISO 9241 stellt Anforderungen und Empfehlungen zur Verminderung von Anfällen aufgrund photosensitiver Reize (PSS) bei der Betrachtung von Bildern auf elektronischen Anzeigegeräten bereit.
Die Anforderungen und Empfehlungen dieses Teils von ISO 9241 wurden für die Anwendung auf Bildinhalte entwickelt. Durch den Begriff „Bildinhalte“ wird auf die Bilder selber verwiesen, unabhängig von Anzeigegerät oder Umgebung, innerhalb derer sie angezeigt werden.
Die Anforderungen und Empfehlungen dieses Teils von ISO 9241 sind zum Schutz der verletzlichen Personen innerhalb der Bevölkerung gedacht, die lichtempfindlich sind und die daher anfällig für Anfälle, die durch aufblitzende Lichter und regelmäßige Muster, einschließlich bestimmter, sich wiederholender Bilder, ausgelöst werden.
ANMERKUNG 1   Die Internationale Fernmeldeunion (ITU) befasst sich mit den Sicherheitsaspekten von Bildern in Bezug auf deren Ausstrahlung. Einige dieser Aspekte werden in ITU-R BT.1702 [2] beschrieben.
ANMERKUNG 2   In ISO/IEC 40500:2012 [W3C Web Content Accessibility Guidelines (WCAG) 2.0] gibt es einige damit verbundene Empfehlungen hinsichtlich des Zugangs zu Inhalten des Internets.
ANMERKUNG 3   Anfälle aufgrund photosensitiver Reize und epileptische Anfälle bedeutet, dass die durch die wiederholten Anfälle gekennzeichneten, chronischen Zustände medizinische Zustände sind. Auf die klinischen Aspekte der Photosensibilität wird in Anhang C Bezug genommen. Visuell hervorgerufene Anfälle sind äquivalent zu PSS.

Ergonomie de l'interaction homme-système - Partie 391: Exigences, analyses et méthodes d'essai de conformité pour la réduction des saisies photosensibles (ISO 9241-391:2016)

ISO 9241-391:2016 spécifie des exigences et fournit des recommandations concernant la réduction des saisies photosensibles (SPS) lors de l'observation d'images sur des afficheurs électroniques.
Les exigences et les recommandations dans la présente partie de l'ISO 9241 sont destinées à être appliquées à des contenus d'images. Le terme «contenus d'images» fait référence aux images elles-mêmes, indépendamment du dispositif ou de l'environnement sur (dans) lequel elles sont affichées.
Les exigences et les recommandations fournies dans la présente partie de l'ISO 9241 sont destinées à la protection de la partie vulnérable de la population, qui risque de faire des crises d'épilepsie photosensible déclenchées par des flashs lumineux et des séquences répétitives, y compris certaines images répétitives.
NOTE 1       L'UIT étudie les problèmes liés à la sécurité des images par rapport à la télédiffusion. Certaines d'entre elles sont décrites dans la Recommandation UIT-R BT.1702.[2]
NOTE 2       Quelques recommandations pertinentes sont fournies dans l'ISO/IEC 40500:2012, Technologies de l'information ? Règles pour l'accessibilité des contenus Web (WCAG) 2.0 du World Wide Web Consortium (W3C) pour l'accessibilité des contenus Web.
NOTE 3       Les saisies photosensibles et l'épilepsie photosensible, c'est-à-dire des troubles chroniques caractérisés par des crises répétées, constituent des états pathologiques. Les aspects cliniques de la photosensibilité sont abordés dans l'Annexe C. Les crises induites par stimulus visuel sont équivalentes aux saisies photosensibles (SPS).

Ergonomija medsebojnega vpliva človek-sistem - 391. del: Zahteve, analize in preskusne metode za ugotavljanje skladnosti za zmanjšanje epileptičnih napadov, sproženih s fotosenzitivnimi dražljaji (ISO 9241-391:2016)

Ta del standarda ISO 9241 podaja smernice za zmanjševanje epileptičnih napadov, sproženih s fotosenzitivnimi dražljaji, enega od treh največjih neželenih biomedicinskih učinkov, ki jih sprožajo slike, predstavljene na elektronskih vizualnih zaslonih. Smernice opisujejo pogoje, ki jih v osnovi ustvarjajo elektronske vizualne slikovne vsebine, predstavljene v domačih in delovnih okoljih, vendar ne na elektronskih vizualnih zaslonih. Smernica v dokumentu je namenjena zaščiti ranljivega dela populacije gledalcev, ki so občutljivi na fotosenzitivne dražljaje ter so zato nagnjeni k epileptičnim napadom, ki jih sprožijo utripajoče lučke in enakomerni vzorci, vključno z določenimi vrstami ponavljajočih slik.

General Information

• Status: Published
• Public Enquiry End Date: 31-Mar-2014
• Publication Date: 04-May-2016
• ICS: 11.020.99 - Other standards related to health care in general
• ICS: 13.180 - Ergonomics
• Technical Committee: VSN - Safety of machinery
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 12-Apr-2016
• Due Date: 17-Jun-2016
• Completion Date: 05-May-2016
• Ref Project: EN ISO 9241-391:2016 - Ergonomics of human-system interaction - Part 391: Requirements, analysis and compliance test methods for the reduction of photosensitive seizures (ISO 9241-391:2016)

Overview

EN ISO 9241-391:2016 (ISO 9241-391) - Ergonomics of human‑system interaction - Part 391 - specifies requirements, analysis and compliance test methods for the reduction of photosensitive seizures (PSS) when viewing images on electronic displays. The standard targets image contents (the images themselves, independent of device or environment) and is intended to protect vulnerable, photosensitive viewers who can experience seizures triggered by flashing lights, rapid image changes or regular visual patterns. Annexes provide clinical context, viewing‑environment guidance and sample test procedures.

Key topics and technical requirements

The standard addresses image safety and practical risk reduction through requirements and recommendations that include:

• Image factors of photosensitive seizures - identification of image features that can trigger PSS (e.g., flashes, repetitive patterns).
• Flashes and rapid changes - guidance on potentially harmful flashes, rapid sequence changes and cumulative risk from repeated exposures.
• Potentially harmful red flashes - special consideration of saturated red stimuli (see Annex E).
• Regular patterns - identification and mitigation of repetitive or high‑contrast patterns that can provoke seizures.
• Prior warning - recommendations for content warnings when risk cannot be fully mitigated.
• Conformance and test methods - defined procedures for analysis and compliance testing, including test methods and a sample conformance procedure (Annex G).
• Informative annexes - clinical aspects of photosensitivity (Annex C), viewing environments (Annex D), and technical guidance (e.g., luminance/signal relations in Annex F).

Note: ISO 9241-391 applies to image contents and does not replace clinical guidance; clinical aspects are informative.

Applications and who uses this standard

EN ISO 9241-391 is relevant to professionals who create, evaluate or certify visual media and displays where image safety is a concern:

• Content creators and producers (broadcast, film, TV, streaming, game developers) - to design imagery that reduces PSS risk.
• Display and device manufacturers - to evaluate image pipelines and provide safe default rendering.
• UX/UI and accessibility designers - to implement safer visual interfaces and provide warnings where necessary.
• Accessibility and compliance testers - to apply the standard’s test methods and conformance procedures.
• Standards bodies and broadcasters - for harmonizing safety practices (noting relation to ITU recommendations).
• Regulatory and health‑safety stakeholders - for risk assessment and consumer protection policy input.

Related standards

• ISO 9241 series (ergonomics of human‑system interaction) - contextual guidance on human factors.
• ISO/IEC 40500:2012 (WCAG 2.0) - related web accessibility recommendations.
• ITU‑R BT.1702 - broadcasting guidance on image safety (informative reference).

Keywords: ISO 9241-391, EN ISO 9241-391:2016, photosensitive seizures, photosensitive epilepsy, image safety, ergonomics, visual displays, PSS reduction, conformance test methods.

Standards Content (Sample)

SLOVENSKI STANDARD
01-junij-2016
(UJRQRPLMDPHGVHERMQHJDYSOLYDþORYHNVLVWHPGHO=DKWHYHDQDOL]HLQ
SUHVNXVQHPHWRGH]DXJRWDYOMDQMHVNODGQRVWL]D]PDQMãDQMHHSLOHSWLþQLKQDSDGRY
VSURåHQLKVIRWRVHQ]LWLYQLPLGUDåOMDML,62
Ergonomics of human-system interaction - Part 391: Requirements, analysis and
compliance test methods for the reduction of photosensitive seizures (ISO 9241-
391:2016)
Ergonomie der Mensch-System-Interaktion - Teil 391: Anforderungen, Analysen und
Prüfverfahren zur Konformität zur Verringerung epileptischer Anfälle ausgelöst durch
photosensitive Reize (ISO 9241-391:2016)
Ergonomie de l'interaction homme-système - Partie 391: Exigences, analyses et
méthodes d'essai de conformité pour la réduction des saisies photosensibles (ISO 9241-
391:2016)
Ta slovenski standard je istoveten z: EN ISO 9241-391:2016
ICS:
11.020.99 Drugi standardi v zvezi z Other standards related to
zdravstvom na splošno health care in general
13.180 Ergonomija Ergonomics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 9241-391
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2016
EUROPÄISCHE NORM
ICS 13.180; 35.180
English Version
Ergonomics of human-system interaction - Part 391:
Requirements, analysis and compliance test methods for
the reduction of photosensitive seizures (ISO 9241-
391:2016)
Ergonomie de l'interaction homme-système - Partie Ergonomie der Mensch-System-Interaktion - Teil 391:
391: Exigences, analyses et méthodes d'essai de Anforderungen, Analysen und Prüfverfahren zur
conformité pour la réduction des saisies Konformität zur Verringerung epileptischer Anfälle
photosensibles (ISO 9241-391:2016) ausgelöst durch photosensitive Reize (ISO 9241-
391:2016)
This European Standard was approved by CEN on 19 December 2015.

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, 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: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 9241-391:2016 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
European foreword
This document (EN ISO 9241-391:2016) 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 September 2016, and conflicting national standards
shall be withdrawn at the latest by September 2016.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
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, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 9241-391:2016 has been approved by CEN as EN ISO 9241-391:2016 without any
modification.
INTERNATIONAL ISO
STANDARD 9241-391
First edition
2016-02-01
Ergonomics of human-system
interaction —
Part 391:
Requirements, analysis and
compliance test methods for the
reduction of photosensitive seizures
Ergonomie de l’interaction homme-système —
Partie 391: Exigences, analyses et méthodes d’essai de conformité
pour la réduction des saisies photosensibles
Reference number
ISO 9241-391:2016(E)
©
ISO 2016
ISO 9241-391:2016(E)
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2016 – All rights reserved

ISO 9241-391:2016(E)
Contents Page
Foreword .iv
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Image factors of photosensitive seizures . 2
5 Ergonomic requirements and recommendations . 3
5.1 General . 3
5.2 Flashes . 3
5.2.1 Potentially harmful flashes . 3
5.2.2 Rapid changes of image sequences . 4
5.2.3 Potentially harmful red flashes . 4
5.2.4 Cumulative risk . 4
5.2.5 Prior warning . 4
5.3 Potentially harmful regular patterns . 4
6 Conformance . 5
6.1 General . 5
6.2 Test methods . 5
6.3 Procedure of conformance. 6
Annex A (informative) Overview of the ISO 9241-series . 7
Annex B (informative) Abbreviated terms . 8
Annex C (informative) Clinical aspects of photosensitivity . 9
Annex D (informative) Viewing environments .10
Annex E (informative) Saturated red .11
Annex F (informative) Typical relation between screen luminance and signal voltage .12
Annex G (informative) Sample procedure for assessing applicability and conformance .13
Bibliography .15
ISO 9241-391:2016(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 on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information.
The committee responsible for this document is ISO/TC 159, Ergonomics, Subcommittee SC 4, Ergonomics
of human-system interaction.
ISO 9241 consists of the following parts, under the general title Ergonomic requirements for office work
with visual display terminals (VDTs):
— Part 1: General introduction
— Part 2: Guidance on task requirements
— Part 5: Workstation layout and postural requirements
— Part 6: Guidance on the work environment
— Part 11: Guidance on usability
— Part 12: Presentation of information
— Part 13: User guidance
— Part 14: Menu dialogues
— Part 15: Command dialogues
— Part 16: Direct manipulation dialogues
ISO 9241 also consists of the following parts, under the general title Ergonomics of human-system
interaction:
— Part 20: Accessibility guidelines for information/communication technology (ICT) equipment and services
— Part 100: Introduction to standards related to software ergonomics [Technical Report]
— Part 110: Dialogue principles
iv © ISO 2016 – All rights reserved

ISO 9241-391:2016(E)
1)
— Part 112: Principles for the presentation of information
— Part 129: Guidance on software individualization
— Part 143: Forms
— Part 151: Guidance on World Wide Web user interfaces
— Part 154: Interactive voice response (IVR) applications
— Part 161: Guidance on visual user-interface elements
— Part 171: Guidance on software accessibility
— Part 210: Human-centred design for interactive systems
1)
— Part 220: Processes for enabling, executing and assessing human-centred design within organizations
— Part 300: Introduction to electronic visual display requirements
— Part 302: Terminology for electronic visual displays
— Part 303: Requirements for electronic visual displays
— Part 304: User performance test methods for electronic visual displays
— Part 305: Optical laboratory test methods for electronic visual displays
— Part 306: Field assessment methods for electronic visual displays
— Part 307: Analysis and compliance test methods for electronic visual displays
— Part 308: Surface-conduction electron-emitter displays (SED) [Technical Report]
— Part 309: Organic light-emitting diode (OLED) displays [Technical Report]
— Part 310: Visibility, aesthetics and ergonomics of pixel defects [Technical Report]
— Part 331: Optical characteristics of autostereoscopic displays [Technical Report]
— Part 391: Requirements, analysis and compliance test methods for the reduction of photosensitive seizures
— Part 392: Ergonomic recommendations for the reduction of visual fatigue from stereoscopic images
— Part 400: Principles and requirements for physical input devices
— Part 410: Design criteria for physical input devices
— Part 411: Evaluation methods for the design of physical input devices [Technical Specification]
— Part 420: Selection of physical input devices
— Part 910: Framework for tactile and haptic interaction
— Part 920: Guidance on tactile and haptic interactions
1)
— Part 940: Evaluation of tactile and haptic interactions
1)
— Part 960: Framework and guidance for gesture interactions
The following parts are under preparation:
— Part 125: Guidance on visual presentation of information
1) To be published.
ISO 9241-391:2016(E)
— Part 333: Stereoscopic displays using glasses
For the other parts under preparation, see Annex A.
vi © ISO 2016 – All rights reserved

ISO 9241-391:2016(E)
Introduction
Recent progress of technology enables us to watch high-definition images, some of which can be
stereoscopic. When those images are projected onto the retina of both eyes and processed as visual
information, undesirable biomedical effects, such as photosensitive seizures, visually induced motion
sickness, and visual fatigue from stereoscopic images can be induced. These undesirable biomedical
effects need to be reduced where feasible. The prevention of these undesirable biomedical effects on
human health has been referred to as “image safety”.
Image safety was first discussed by the ISO in the ISO/COPOLCO with respect to the users of image
products. Then, in 2004, the ISO/International Workshop on Image Safety was held and resulted
[1]
in the publication of ISO/IWA 3:2005 as the international workshop agreement. Following those
discussions, the study group (ISO/TC 159/SC 4/SG on Image Safety) continued to evaluate strategies
of the international standardizations until 2009. The basic concept of Image Safety is common with
[18]
ISO/IEC Guide 71:2014 , in which the idea is that accessibility to and usability of products and
services should be available to all people.
This part of ISO 9241 will help promote the production of safer images by reducing the risk of
photosensitive seizures, and thereby result in the wider distribution of images that are free from
constraints on which consumers can view them. A small proportion of the population is susceptible to
seizures and other neurological effects when watching motion picture and video content with certain
display features. Since these reactions depend on individual susceptibility have been documented with
programming viewed through cathode-ray tube (CRT) displays, there is as yet less experience with
high-definition displays.
This part of ISO 9241 belongs to a family of human-system interaction standards. Readers who need
guidance on other aspects of human-system interaction should refer to the ISO 9241-series.
INTERNATIONAL STANDARD ISO 9241-391:2016(E)
Ergonomics of human-system interaction —
Part 391:
Requirements, analysis and compliance test methods for
the reduction of photosensitive seizures
1 Scope
This part of ISO 9241 provides requirements and recommendations for reducing photosensitive
seizures (PSS), while viewing images on electronic displays.
The requirements and recommendations in this part of ISO 9241 are designed to be applied to image
contents. By image contents, reference is made to the images independent of the device or environment
in which they are displayed.
The requirements and recommendations in this part of ISO 9241 are for the protection of the vulnerable
individuals in the viewing population who are photosensitive and who are therefore liable to seizures
triggered by flashing lights and regular patterns, including certain repetitive images.
NOTE 1 ITU considers the image safety issues in relation to broadcasting. Some of these are described in
[2]
ITU-R BT.1702.
NOTE 2 There are some related recommendations in ISO/IEC 40500:2012, W3C Web Content Accessibility
Guidelines (WCAG) 2.0, for web contents accessibility.
NOTE 3 Photosensitive seizures and photosensitive epilepsy, that is, chronic conditions characterized by
those repeated seizures are medical conditions. Clinical aspects of photosensitivity appear in Annex C. Visually
induced seizures are equivalent to PSS.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. 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
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 9241-302 and the
following apply.
3.1
flash
pair of opposing changes in relative luminance
Note 1 to entry: A “pair of opposing changes” is an increase followed by a decrease or a decrease followed by an
increase.
3.2
electroencephalogram
EEG
record of electrical changes caused by neuronal activities in the brain through electrodes attached to
the scalp
ISO 9241-391:2016(E)
3.3
photoparoxysmal response
PPR
EEG (3.2) response to flash (3.1) or pattern, consisting of spikes, spike–waves, or intermittent slow
waves, which include spike-waves at around 3 Hz that can be detected bilaterally and simultaneously in
all areas of the scalp
3.4
photosensitivity
human individual sensitivity to flashing or intermittent light stimulation and/or visual patterns,
evidenced by the occurrence of a photoparoxysmal response (3.3) in the EEG (3.2)
Note 1 to entry: Visual sensitivity is a term recently sometimes used as an alternative to the term
“photosensitivity.”
3.5
photosensitive seizure
PSS
[3]
epileptic seizure triggered by visual stimulation as a result of photosensitivity (3.4) in a human individual
3.6
photosensitive epilepsy
chronic neurological condition characterized by recurrent photosensitive seizures (3.5), either
convulsive or non-convulsive seizures, such as absence seizures
4 Image factors of photosensitive seizures
A photosensitive seizure may be produced in susceptible individuals by flashing lights or certain
[3][16]
regular patterns. A visual stimulus tending to provoke a seizure is bright light flashes of a certain
[4]
number per second. The light must also fill a large part of the visual field. For the light flashes, colour
[5][12]
changes to or from saturated red, instead of luminance changes, also tend to provoke a seizure.
Another potentially provocative visual stimulus for some individuals with photosensitivity is regular
[6]
patterns with a certain number of bright stripes per a certain area. The pattern must also fill a
large part of the visual field, while the provocation depends on whether the patterns are stationary or
[7][16][17]
oscillating (including flashing).
[3][14]
PSS can be reduced, to some extent, by considering factors such as those shown below. These
[13][15]
factors need to be considered at the same time in an appropriate balance.
— Potentially harmful flashes:
— Luminance and contrast
— Area of visual field
— Number of flashes per unit time
— Rapid changes of image sequences
— Potentially harmful red flashes:
— Colour
— Area of visual field
2 © ISO 2016 – All rights reserved

ISO 9241-391:2016(E)
— Number of flashes per unit time
— Cumulative risk:
— Duration of flashing
— Potentially harmful regular patterns:
— Clearly discernible stripes
— Number of stripes and area of visual field occupied
— Moving/stati
...