Digital BW, The Print

Hi Martin,

> > > Ratio of minimum and maximum contrast.
> >
> > B-b-b-b-b-but Martin, isn't maximum contrast (dMax - dMin), and minimum
> > contrast the "smallest discernable [tonality]"?
>
> Austin,
>
> The problem I have is what is doing the discerning. I know that my eye
> cannot discern as small a change in tone as a densitometer for
> example. Also
> if the print changes tones in increments smaller than my eye can detect,
> then the minimum contrast would be determined by my eye and not the print.
> The idea of min/max contrast perhaps makes some sense to me but I am still
> skeptical of how it could be put to good use.  I need to mull this over a
> bit.

I understand and agree.

<snip>

> > > The equation is just a subtle change on
> > > the basic max
> > > to min ratio
> >
> > What's the change?  The definition of "min" and "max"?
>
> No it is a clarification of what we are taking the dynamic range of. The
> dynamic range of contrast would not appear to be the same as the dynamic
> range of density.

Hum.  I had to read that a few times.  In a way I agree.  Density is a
static value, and really can be only a single value in and of it self
(though it's understood it is a relative value, based on a calibrated
density scale...).  Contrast isn't static...it requires another thing to be
contrasted against.  In that, I agree...and fits the term "dynamic" much
better.

> > <snip>
> >
> > > Austin is
> > > not wrong in
> > > applying his contrast ratio to a photographic print but he
> has failed to
> > > demonstrate how this would be done or what value it would have when
> > > comparing two printing mediums.
> >
> > For me, that's a separate issue...I wanted to get to the point where the
> > basic concept was understood first.  I take it you now understand/agree
> with
> > the statement "dynamic range of a photographic image is
> (maximum contrast
> /
> > minimum contrast)", and not the same as the density range?
>
> I better understand the relationship you are trying to define but I have
> long realized that it was something different from the density
> range. Now as
> to which is the more useful concept I am not sure.

We are in full agreement and understanding here ;-)

> Would it be
> inappropriate
> for a print to have more than one dynamic range? Each for different
> properties or relationships between those properties? Or perhaps the word
> dynamic range has been used in so many different ways we need some new
> terminology?

I do believe the dynamic range of the printing system can be determined, as
well as of the paper one is printing on.  Quite easily in fact.  Obviously,
as has been well pointed out, the actual dynamic range of A print, in and of
it self, is a far more complex issue.  I agree.  I have to sit with that for
a while when I get some time.  I believe I understand how it can be done,
but obviously, haven't spent the time doing it.  It would be interesting (at
least to me) though.

Regards,

Austin