RE: filmscanners: brief density math lesson...

["Austin Franklin" <darkroom@ix.netcom.com>]

> > This is a common misconception - relating bit depth to dynamic range.
> > The number of bits that the A to D converter produces
> > determines how finely the range of the CCD is quantized
>
> It also sets the maximum possible dynamic range (OD) which the system is
> capable of encoding. This is all about ratios linearly encoded.

In practical practice that is absolutely true.  That assumes equal steps,
which is a very valid assumption, since that's how A/D converters, well,
work ;-)

One could encode any density range in two bits (three states are
needed)...but that wouldn't be encoding the density values linearly, which
is what you really want from the scanner...not just to know when the value
is >=DMax, <=DMin or in-between.

Ever hear the joke about the guys in prison, over the years, instead of
telling the same jokes over and over again, they just use a number "Hey,
#56" and people laugh...