[sane-devel] some english words

Martin Collins martin@mkcollins.org
Sat, 23 Oct 2004 17:43:15 +0100

On Sat, 23 Oct 2004 14:03:57 +0200
Giuseppe Sacco <eppesuig@users.sourceforge.net> wrote:

> I am updating the italian translation for sane-backends and I have a
> questiong about radiance and brightness: are these synonims in
> english? If they are then I will translate both with "luminosit=E0",
> otherwise I have to understand what is the difference between them.

Radiance implies the emission of light, brightness could also apply
to reflection.

Depending on context radiance might refer to absolute intensity (i.e
the number of photons emitted) and brightness to apparent intensity
(i.e. the number of photons detected).

Brightness is one coordinate of the HSB colourspace (black-white) or
the mean of R,G and B values.
Strictly speaking it is not a synonym of radiance which is a measure
of the intensity of a light beam.
Luminosity is the power output of a light emitter.

However, in this context I doubt we are dealing with the strict meaning
of radiance so it is fairly safe to assume that brightness, radiance
and luminosity are all referring to the same kind of thing.