Definition: | luminance of a comparison field in which the radiation has the same relative spectral distribution as that of a Planckian radiator at the temperature of freezing platinum and which has the same brightness as the field considered under the specified photometric conditions of measurement ; the comparison field must have a specified size and shape which may be different from that of the field considered
unit: cd · m-2
NOTE – A comparison field may also be used in which the radiation has a relative spectral distribution different from that of a Planckian radiator at the temperature of freezing platinum (T = 2042 K), if the equivalent luminance of this field is known under the same conditions of measurement.
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