Definitions of units for luminance

apostilb

Unit of luminance. 1 apostilb equals 1/π cd/m², about 0.31831 nit.

blondel

Unit of luminance. 1 blondel equals 1/π cd/m², about 0.31831 nit.

candela per square meter

SI unit of luminance (symbol cd/m²).

footlambert

A Non-SI unit of luminance (symbol fl) . A foot-lambert equals 1 / π candela per square foot, or 3.4262591 candelas per square meter (nits). It is named after Johann Heinrich Lambert, a German mathematician, physicist and astronomer.

lambert

A non-SI unit of luminance (symbol La). It equals 1 / π candela per square centimeter, or 3183.1 candelas per square meter (nits).

nit 

U.S. customary unit of luminance for SI unit candela per square meter (symbol nt). The unit is from latin word "nitere" meaning "to shine".

skot  

Unit of luminance. One skot equals 10^-3/π cd/m² or one thousandth of lambert.

stilb

A CGS unit of luminance (symbol sb), which is one candela per square centimeter or 10⁴ nits (candela per square meter).