Definition of luminance in US English:

luminance

noun

Physics
  • 1The intensity of light emitted from a surface per unit area in a given direction.

    • ‘This principal component direction is taken to be the luminance direction.’
    • ‘The specifications are commonly based on the 2 - D illuminance, luminance, intensity, chromaticity, and polarization distributions.’
    • ‘Nits are also a measure of luminance, in so many candela per square metre.’
    1. 1.1 The component of a television signal which carries information on the brightness of the image.
      • ‘These signals are also what is referred to as Y / C signal or luminance and chrominance.’
      • ‘Note that the green channel has twice the number of photodetectors as red or blue (this is because the majority of luminance information is carried in the green channel).’
      • ‘The Y component is the luminance of the signal (not the color yellow), and delivers the gray scale image.’
      • ‘It is thus possible to quickly restore the light quantity control function by inputting the current luminance signal to an iris controller before the display of the still picture is stopped.’
      • ‘A sequence of passes separates the luminance and chrominance information from the composite video signal and demodulates the color carrier to separate out color information.’

Origin

Late 19th century (as a general term meaning ‘light, brightness’): from Latin luminant- ‘illuminating’ (from the verb luminare) + -ance.

Pronunciation

luminance

/ˈlumənəns//ˈlo͞omənəns/