Diffusion Factor
2-1-230
Diffusion Factor (of a diffusing surface, by reflection or by transmission)
The ratio of the mean of the values of luminance measured at 20 and 70 degrees to the luminance measured at 5 degrees from the normal, when the surface considered is illuminated normally.
Symbol: s
Note 1: The diffusion factor is intended to give an indication of the spatial distribution of the diffused flux. It is equal to 1 for every uniform diffuser, whatever the value of the diffuse reflectance.
Reference: C.I.E. (extract)
Note 2: The full text of the C.I.E. definition explains the limitations within which this form of definition can be applied.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
