| product of the luminance in a specified direction and the apparent area of the pupil (natural or artificial) seen from that direction Note 1 to entry: Conventional retinal illuminance applies to situations where the eye is viewing a surface of uniform luminance larger than the area of the natural or artificial pupil. Note 2 to entry: The conventional retinal illuminance is expressed in candela (cd), candela per square metre times square millimetre (cd·m−2·mm2), or troland.
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