EN ISO 9241-391:2016 PDF

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.