Foot-Lambert

Foot-Lamberts (fL) is a unit of measurement used to measure the luminance or brightness of an object. It is defined as one lumen per square foot and is commonly used in the imaging, video and projection industries. Foot-Lamberts are expressed as a ratio of light reflected off a surface, such as a movie screen or front projection surface, divided by the amount of light that actually falls on the surface. This allows projectors to be set up for optimum performance in terms of brightness and contrast levels.