Lumen
From The Glossary of Digital Photography
A unit of measure for luminous flux. A lumen indicates the amount of light coming from a light source, but it does not translate directly into brightness unless a specific area is taken into a consideration. As an example, a single 100-watt light bulb will not provide enough light to walk around a large enclosed auditorium. Yet that same bulb in a small closet is nearly overwhelmingly bright. See also lux; candela (cd)
