Digital BW, The Print

Hi Bob,

Well, Martin is a very bright guy, and I respect his views, experience and
opinion on most every subject...but on this issue, we obviously disagree...

The basic equation for dynamic range stands in and of it self, no matter
what pedestrian definitions people want to "interpret" to it.

Dynamic Range (dB) = 10log10 (largest signal/smallest discernable signal)

The diagram I provided:

http://www.darkroom.com/Images/DynamicRange01.jpg

provided unambiguous definitions for largest signal and smallest discernable
signal, which are the only two terms that need definition, since the rest of
the equation is solely based on these two definitions.

Therefore, dynamic range is basically a measurement of the number of
different discernable "signals" within a particular range, and in the case
of print images, discernable tones.

Density range and dynamic range are not the same.  Density range is purely a
static measurement of the dMax - dMin.  It has nothing to do with dynamic
range (or they would have called it dynamic range ;-), as dynamic range, by
definition, takes into account the "smallest discernable signal", and
density range does not.

dMin is not the same as the "smallest discernable signal", as dMin can be
way above the noise floor.  This is obvious in negative film, since the
density of the film base is substantially larger than the density values
you'll get between "discernable" tones in the image.

Basically, I believe that's what I claim in a nut shell, and the basic
points Martin "disagrees" with.

Regards,

Austin


> Oh dear,
>
> I thought I'd just understood this argument!
>
> Back to color printing I think.
>
> Bob Frost
>
>
> ----- Original Message -----
> From: "Martin Wesley" <mwesley250@...>
>
>
> >
> > Unfortunately, I feel I understand the matter reasonably well for my
> > purposes. I had hoped that providing other sources would help you
> understand
> > what I was saying. The dialogue has helped me to clarify and confirm my
> > thoughts.