Irradiance
The irradiance Ee (“e” for energetic) or radiant flux density is the total power of electromagnetic energy passing through a surface and is a radiometric quantity. It correctly describes the “intensity” of lighting in image processing.
The SI unit is W/m² (=power per area)
In order to quantify the “intensity” for lighting in the visible spectral range, the term illuminance is often used, which takes into account the sensitivity of the human eye.
