Re: So it's the bits? (Was: filmscanners: Sprintscan 120 now

[Tony Sleep]

On Wed, 10 Jan 2001 19:41:35 +1100  Julian Robinson ([EMAIL PROTECTED]) 
wrote:

> I am having a fundamental problem comprehending why the number of bits is 
> even vaguely related to any supposed density range.  I understand the maths 
> quoted here and in many other posts, but fail to understand why the fact 
> that the ratio of smallest bit size to largest number represented should be 
> related to density range.

Because at the ADC, optical brightness ratios (as analogue voltages) are mapped to 
bits in a linear fashion. 

There was a long and involved discussion about this a while back. You should be 
able to locate the thread at the archive at http://phi.res.cse.dmu.ac.uk/Filmscan/ 
 - I think it was entitled 'Bit depth vs. OD'.
 
Regards 

Tony Sleep
http://www.halftone.co.uk - Online portfolio & exhibit; + film scanner info & 
comparisons