Detail of GB/T 44382-2024

Introduction of GB/T 44382-2024

GB/T 44382-2024 Ergonomics - Accessible design - Specification of age-related luminance contrast for coloured light 1 Scope This document specifies the age-related luminance contrast of any two lights of different colour seen by a person at any age, by taking into account the age-related change of spectral luminous efficiency of the eye. This International Standard provides a basic method of calculation that can be applied to the design of lighting, visual signs and displays. It applies to light, self-luminous or reflected, in visual signs and displays seen under moderately bright conditions called photopic vision and whose spectral radiance is known or measurable. It does not apply to light seen under darker conditions called mesopic or scotopic vision. This document specifies the luminance contrast for people aged from 10 to 79 years who have had no medical treatment or surgery on their eyes that may affect their spectral luminous efficiency. This document does not apply to visual signs and displays seen by people with colour defects whose spectral luminous efficiency is different from those with normal colour vision, nor those seen by people with low vision. 2 Normative references The following refererenced documents are indispensable for the application 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. GB/T 2893.4-2013 Graphical symbols - Safety colours and safety signs - Part 4: Colorimetric and photometric properties of safety sign materials (ISO 3864-4:2011, MOD) Note: There is no technical difference between the referenced content of GB/T 2893.4-2013 and the referenced content of ISO 3864-4:2011. ISO 9241-303:2011 Ergonomics of human-system interaction - Part 303: Requirements for electronic visual displays 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 luminous efficiency (V for photopic vision and V' for scotopic vision) The ratio of the radiant flux weighted by the harmonic luminous efficiency to the corresponding radiant flux under specific luminous conditions. [SOURCE: CIE S 017:2020, 17-21-094] 3.2 spectral luminous efficiency ratio of the radiant flux at wavelength λm to that at wavelength λ, such that both radiations produce equally intense luminous sensations under specified photometric conditions and λm is chosen so that the maximum value of this ratio is equal to 1 Note 1: Adapted from CIE S 017:2020. Note 2: The values for spectral luminous efficiency in photopic vision are given in ISO/CIE 23539:2023. 3.3 radiant flux; radiant power Φe; Pe; Φ; P change in radiant energy with time Note: The radiant flux is expressed in watts (W). [SOURCE: CIE S 017:2020, 17-21-038] 3.4 age-related photopic spectral luminous efficiency Va(λ) spectral luminous efficiency defined as a function of age, a 3.5 luminance contrast ratio between the higher luminance, LH, and lower luminance, LL, that defines the feature to be detected Note 1: If measured by contrast modulation (or Michelson contrast) it is defined as: or, if measured by contrast ratio (CR), it is defined as: Note 2: Contrast ratio, CR, is often used for high luminances. When near the luminance-detection threshold, some use the following form (also known as Weber contrast): Note 3: For some but not all displays, area-luminance targets can be used to approximate the luminances that define the feature to be detected because pixels are discrete and near-area luminance is sufficiently uniform. Note 4: Equation (2) is used in this International Standard. Equations (1) and (3) may also be used to calculate age-related luminance contrast. [SOURCE: ISO 9241-302:2008, 3.1.7] 3.6 age-related luminance contrast Ca(λ) luminance contrast defined as a function of age, a Note: The formula is given in Equation (4). 3.7 photopic vision vision by the normal eye when it is adapted to levels of luminance of at least several candelas per square metre [SOURCE: CIE S 017:2020, 17-22-016] 4 Age-related luminance contrast The equation for age-related luminance contrast, Ca, is derived from the luminance contrast equation in which the luminance term is accommodated to the value that takes into account the age-related change of spectral luminous efficiency. See Table 1. Equation (4) shall be applied when age-related luminance contrast is calculated for light P1 and light P2 with spectral radiance of Le,λ,1 and Le,λ,2, respectively.

Contents of GB/T 44382-2024