Lighting Design Glossary

Reflectance
Diffuse Reflectance
Albedo

(Term of radiometry/photometry/Radiance)

Reflectance is the ratio of incident luminous flux upon a surface which is reradiated in the visual spectrum.

Albedo is another Term for Reflectance.

Diffuse reflectance is the ratio of the flux reradiated by diffuse reflection (from a lambertian surface).

Unit of reflectance is percent (%) or a factor between 0 and 1.