Digital BW, The Print

Roy,

I'm sensing that some of us have locked horns when we are probably more in
agreement than out of agreement. Perhaps if we all surrender a little ground
we can turn this back into a useful discussion.

Is it possible that *some* people used the term dynamic range to describe
something one step more complex than density range? I think behind Austin's
absolutist rhetoric that is what he's saying.

Working with my sense of logic, which doesn't prove anything, let's look at
the bigger picture. Lets consider a common situation we as photographers
experience. Say through careful exposure and development we have a negative
with a beautiful delicate distribution of tones throughout it's useful
range. It would perfectly fit all it's tones on a given grade 2 paper. Let's
say that print's density range would be 2 units. If we could measure the
print on a pixel by pixel basis it would yield a perfect distribution of
tones in a histogram, right to the ends with no clipping. We could then
print that negative on a grade 3 paper, which may also yield a density range
of 2 units, but we "clip" tones from the image on both ends due to increased
contrast. It's histogram shows the clipping accordingly. We could even
extend the scenario to where we keep the print on grade 3 paper, but dodge
the shadows and burn the highlights, thus maintaining a higher internal
contrast through the midtones, without clipping the ends. It's density range
is still 2 units, and it's histogram looks more like the grade 2 print, at
least at the ends.

Something *is* different in each of these prints, but it is not the density
range. Is it possible that some people would say that the grade 2 print had
a greater dynamic range than the straight grade 3 print, and that the
manipulated grade 3 print might have had the greatest dynamic range of the
three? If not dynamic range, what would be that term?

Todd





> --- In DigitalBlackandWhiteThePrint@y..., "Austin Franklin" <darkroom@i...>
> wrote:
>> Roy,
>> 
>>> So, how can we here is our niche, talk about coming up with a new idea,
>>> new concept of what "dynamic range" means?
>> 
>> No one is coming up with any new concepts...  "We" are merely pointing out
>> that the term has been "misapplied" in this "field", and that it attributes
>> a different property than, though is loosely related to, density range.
> 
> Austin,
> 
> I think Todd's "lost in the trees at points and loose sight of the woods"
> quote is right on.
> 
>> 
>>> We a just a part of a large
>>> community of imaging that long time ago has defined and has commonly used
>>> this term to mean sometime very specific.
>> 
>> Can you show evidence of this?
> 
> I think the Ansel Adams book and the Real World Scanning references were
> pretty relevant.  I'm glad to see you have read the scanning book.  You
> quoted one sentence that contained "dynamic range describes the actual
> limits of how many tones the scanner can really differentiate from light to
> dark".  You seem to be associating:  dynamic range <--> how many tones,
> when I think the real association is:  dynamic range <--> actual limits.
> Reading just this one sentence might be a little ambiguous, but read the whole
> paragraph.  Immediate following this sentence is the staircase example:
> dynamic range <--> height of staircase,  bit depth <--> number of steps.
> Later on he compares a scanner with "enormous dynamic range but only
> 256 steps" and a scanner with "lots of tiny steps and tiny dynamic range".
> There's no way to interpret these two examples to mean dynamic range
> is a measure of number of tones or steps!
> Do you wish to claim that this book and the three guys who wrote
> it are wrong and misuse and misdefine the term??
> 
> If you look at the Adam's book there's a diagram that explicitly shows
> "dynamic range".  He's talking about exposure and shows very clearly
> dynamic range going from about Zone I to Zone IX saying its the "useful"
> range of light values in the scene.  He even mentions how this dynamic
> range of light values maps directly into the range of "useful" densities on
> the negative.  Would you like to claim he's all wrong, too?
> 
> Please consider your position as it relates to these references.  These
> are both very explicit references to dynamic range as it relates to imaging.
> 
> Regards,
> Roy
> 
> 
>> 
> ... monitor stuff snipped
> 
>> 
>> Austin