The fraction of incident radiant flux returned by reflection, for specified wavelength, angle of incidence and collection directions.
A function relating reflected radiance in one direction to incident irradiance from another direction at a surface location. A local nonemissive, nonfluorescent optical reflection model integrates over incident solid angle to obtain outgoing radiance. Transmission, wavelength conversion and nonlocal transport need additional models.
The ratio of reflected to incident radiant flux as a function of wavelength, under specified geometrical and illumination conditions. Unlike a perceived colour, spectral reflectance describes a physical response; perceived colour also depends on the incident spectrum and the observer.
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Reflectance is a measure of how much light or other electromagnetic radiation is reflected by a surface compared to the amount that hits it. It is typically expressed as a percentage or a ratio between 0 and 1. A value of 0 means that no light is reflected (all light is absorbed), while a value of 1 means that all light is reflected.