ISO 24502:2010

Overview

ISO 24502:2010 - Ergonomics - Accessible design - Specification of age-related luminance contrast for coloured light provides a standardized method to assess how two differently coloured lights are perceived across ages. The standard accounts for the age-related change in photopic spectral luminous efficiency of the human eye and defines an age-related luminance contrast calculation for people aged 10–79 years. It applies to self‑luminous or reflected light in visual signs and displays under photopic (moderately bright) conditions where spectral radiance is known or measurable.

Key topics and requirements

• Age-related spectral weighting: Uses age-dependent photopic spectral luminous efficiency V_a(λ) (tabulated in decade steps) to weight spectral radiance across 380–780 nm.
• Contrast definition: Provides the formula for age-related luminance contrast C_a derived from luminance terms weighted by V_a(λ). The standard primarily uses the contrast ratio (CR) definition but notes Michelson and Weber forms may also be applied.
• Spectral radiance input: Applies when the spectral radiance of each light (W·m⁻²·sr⁻¹·nm⁻¹) is known or measurable and summed (commonly in 5 nm steps).
• Scope limits:
  • Applies only to photopic vision (not mesopic or scotopic).
  • Covers observers aged 10–79 with normal colour vision and without medical eye alterations affecting spectral efficiency.
  • Does not apply to people with colour vision defects or low vision.
• Referenced guidance: Links to related ergonomics and photometry documents (ISO 3864 series, ISO 9241 parts, ISO/TR 22411, CIE colorimetry and photometry standards).

Applications and users

ISO 24502:2010 is useful for professionals concerned with visibility and accessibility of coloured light:

• Lighting designers and architects ensuring signage and displays remain legible for older adults
• Signage and safety sign manufacturers validating colour combinations and luminance contrasts
• Display and UI engineers optimizing colour contrast for control panels, dashboards, and public information systems
• Human factors / ergonomics practitioners and accessibility consultants assessing inclusive visual design
• Transport authorities and facility managers specifying accessible wayfinding and safety signage

Practical use cases include designing colour pairs for signage, calculating required luminance levels for displays, and verifying that coloured visual information remains distinguishable across age groups.

Related standards

• ISO/IEC Guide 71 (accessible design principles)
• ISO/TR 22411 (age-related visual efficiency guidance)
• ISO 9241-302 / ISO 9241-303 (visual display ergonomics)
• ISO 3864 series (safety colours and signs)
• CIE colorimetry and photometry references (ISO 23539 / CIE S 010, CIE 15)

Keywords: ISO 24502:2010, age-related luminance contrast, accessible design, photopic vision, spectral radiance, signage design, ergonomics, visual displays, colour contrast.