JIS S 0031:2004

This Standard specifies the method of assessment of the visual efficiency of light and the visivility based on it when the target to be observed of ages from the young to the elderly looks at the light source and the object using the age-related relative luminace in consideration of ages of the target. In addition, this Standard applies to the light source and the object of which spectral radiance is known or measurable, which are seen under a bright environment called photopic vision, and does not apply to those which are seen under a dark environment called mesopic vision and sctopopic vision.