[Radiance-general] dynamic range

[Axel Jacobs]

> I have another question on this - how we compute Dynamic Range?
> If for example: the brightest pixel has luminance 50 000 cd/m^2 and the
> darkest one 5 cd/m^2
> is dynamic range 50 000/5 = 10 000:1? is that correct?
> (i.e. 4 OoM)

That looks right. It's easier in exponential notation -- the division
becomes a subtraction then: 5*10^5 / 5*10^1 = (5/5) * 10^(5-1) = 10 000

> And something more... is there any standard threshold, that "seperates"
> dynamic range to High and Low?

Not to my knowledge. However, it's save to assume that all images are low
DR, except for the ones that explicitly say that they are high. They must
then be stored in a file format that supports HDR, _and_ be created
suitably. It is possible to have a LDR image stored in a HDR file (e.g.
falsecolor RADIANCE images).

The difference between the dynamic range of LDR and HDR images is several
orders of magnitude ;-) (Just winding you up...)

Cheers

Axel