Luminance, illuminance, intensity, flux, etc. : what are the differences?

2.1.	Luminance, illuminance, intensity, flux, etc.: what are the differences?

An optical source emits a luminous flux (F) of energy toward a sensor. This flux propagates from the source to the sensor.

Relationships between luminous parameters are summarized into the below table:

Luminous parameters

Luminance is a quantity representing the brightness of sources independently from its size and its emitting cone. This value is consequently often used to compare tow sources.