Photometric counterpart of @R05037@, producing the visual sensation called @BT07337@. Typical units are: \(\text{candela}\ \text{m}^{-2}\) (\(\mathrm{nit}\)), \(\text{candela}\ \text{cm}^{-2}\) (\(\mathrm{stilb}\)), \(\mathrm{foot}\ \mathrm{lambert}\) (\(2.426\ \text{nit}\)). As with all photometric quantities, luminance does not refer to a specific @W06659@, but applies to light emitted by a standard source (formerly a 'standard international candle', now a blackbody radiator emitting at the temperature of solidifying platinum, \(2042\ \text{K}\)). Conversion from photometric units to radiometric units (e.g. \(\text{J s}^{-1}\)) requires convolution over @W06659@ of the relative spectral response of the human eye (photopic response tables).