RE: filmscanners: Nikon Scan & VS Negative dynamic range

[shAf]

Tony writes ...

> On Wed, 5 Sep 2001 23:29:34 -0400  Austin Franklin
> ([EMAIL PROTECTED]) wrote:
>
> > Mapping the input data into 8 bit values has nothing to do with the
> > dynamic range of the A/D data
>
> Arrgh... not this again! :-)
>
> Actually it does, ...
> ...

  Correct!!! ... "linearity" is the keyword, that is, the scanner's driver
cannot map the CCD to RGB data non-linearily without losing information.
The only method, without losing info, is to map the linear CCD to greater
RGB depth.  And if you take a the math a bit further you realize 12bit depth
is all that is required to cover the most extreme optical densities (...
altho there's nothing wrong with having a couple of bits of headroom, as
long as the scanner had a true ability to scan OD=3.3 ...)

shAf  :o)