Luminosity & luminance

  • Luminosity signifies the total amount of visible light emitted by a light source and is measured in watts or lumens. It is a measure of the raw power output of light.
  • Luminance, on the other hand, tells us about the perceived brightness of that light as perceived by an observer. It considers multiple factors:
    • The luminosity of the source
    • Reflection off the surface receiving the light
    • The human eye’s sensitivity to different wavelengths
  • A powerful light source (high luminosity) might shine on a dark surface (low reflection), resulting in a lower perceived brightness (lower luminance).
  • Conversely, a weaker light source shining on a highly reflective surface could still lead to a higher perceived brightness due to the reflection boosting the received light.