Digital BW, The Print

Austin,

I sense you don't have the time to continue this thread to a conclusion now,
so without further response from you this will be my last post, at least to
you, on this topic. But I post this as a summary of where I stand. I believe
these are some of the issues your report will need to address to be
persuasive to a larger audience.

There have been three overlapping issues at play in this discussion.

A) What does the term Dynamic range refer to, and how is it distinct from
any other range.

B) How is DyR ascertained, and to what components is it applicable?

C) Why, in continuous tone photography, is the term DyR used so broadly
differently than what you established in A? There are pedestrian audiophiles
too, but the usage has remained steady in that field.

I think you've done a nice job with A, kudos, it wasn't easy; but B and C
are still lacking. I will try to address them separately below, but it
rambles, and there is a lot of overlap.

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How is DyR ascertained, and to what components is it applicable?


I believe your efforts so far have been more keenly geared toward a
discussion of the DyR of a print as the output of a "system". I've been
looking at that, but also at the print as an "object", where the system may
be unknown.

If you decide that DyR is more a measure of a system than an object then I
think we may have the basis for agreement. When I say "system:" I mean a
process where you feed known input values then measure/observe how well
(probably how linearly (within whatever scale you are working in, Roy))
those values get mapped upon output.

I think the notion that DyR applies more to a system than an object is not
far fetched. An audio system has a DyR, but you can't determine the DyR of a
loudspeaker without knowing what values are being fed to it, can you? I'd
think not, because you don't know if the sound you measure coming out
contains the loudspeaker's own noise or a faithful rendering of noisy input
values. You also don't know if the max and min are its limitation, or the
input value's. And so it goes for a print when viewed apart from a system.

As a side issue, if you had said that the Piezo system allows for better
tonal separation or delineation within its range than silver, there may
never have been an argument. But you said Piezo prints have better DyR than
silver, and that DyR means number of tones. But with Piezo's LOWER density
range, and on the matte papers we usually use, HIGHER noise than the more
common smooth surfaced silver papers, it is off to a poor start in the DyR
equation, relative to silver. THAT is what makes the DyR issue complicated.
With less DnR, and more noise, where is it's (purported) superior DyR
from??? This is critical and you have yet to address it.
 
As I've maintained, I believe the key to your logic lies in Piezo's better
linearity* (which is not true of all digital workflows), but the DyR
equation [(max-min)/noise] does not even address linearity. You were very
critical to those who were loose with the terms "max" and "min", but I feel
you have been equally loose with "noise". Noise seems to be a big catchall
phrase which seems to imply, "where the system fails", or "where linearity
is not maintained". I will address noise again in the next section.

(* By linearity I mean input values may get compressed or expanded to fit
into the next generation's range, but they do so in a uniform fashion, with
no more compression/expansion to one part of the range than another.)

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Why in continuous tone photography is the term DyR so broadly used
differently than what you established in A? There are pedestrian audiophiles
too, but the usage has remained steady in that field.


It comes full circle to where this began with Martin. He questioned if you
did take the DyR approach as you know it, which was probably born in the
field of electronics, and apply it to a chemical based process like a print,
would the concepts still apply; and to which I added: should the approach be
the same? Or, is the "noise" insignificant, such that you can just drop it,
or perhaps consider it numerically as one, which would I guess imply
linearity, and consider RANGE as dynamic range, and presume stepless tones -
at least from the standpoint of human perception - are available within that
range? 

You've asked, what then is dynamic about that range? What makes the range
dynamic is its degree of malleability. That's why conventional silver papers
have a greater DyR than a material like litho. Silver's range can vary
substantially based on exposure and development. Litho materials have very
strict thresholds with very little flexibility. However you handle litho
material you get the same range, not so conventional materials.

Here's an analogy. Looking at a rubber band, what is relevant, its range, or
the number of intermediary positions within that range? I think range. Even
if you could count its intermediary positions, why would you, when
continuity can be assumed?

Rubber bands, like silver prints, have a high DyR, while twine, like litho,
has low DyR. Now in your DyR equation, what distinguishes DyR from density
range? Noise.

But in looking at the rubber band vs twine, what distinguishes their dynamic
range? The malleability of their range - certainly not noise. See, the DyR
equation doesn't uphold the concept here. And if it seems silly to be
thinking of the DyR and noise of rubber bands and twine, so might it be for
prints. 

Now there is one ambiguity in all that, which relates to "B" above. I said
range may be all that need be considered in a print, but clearly a
conventional print (by virtue of it's malleability) is *capable* of far more
tones than a litho print (if there is such a thing as litho paper), in spite
of the fact that they may share the same density range. Do I wish to ignore
that fact?

No, but unutilized capability is irrelevant to an object. It's like saying a
circle isn't a circle because it could have been a square.

Take a litho neg and make an enlargement of it onto two papers: 1)
conventional silver paper, and 2) a litho paper - such that the prints have
the same DnR. In this instance the prints, as objects, will have the same
DnR AND DyR. They have to, they will be essentially the same print,
regardless of whatever unutilized capability either may have.

This speaks to the difference between a system, which has capability, and an
object, which just is. A print is an object. A print as object, like a
rubber band, just might need only be defined by its range.

If one *were* ambitious enough to try to count a rubber band's intermediary
positions (tones) should they use the DyR [(max-min)/noise] formula, or
would something else be required? First I'd wonder what would constitute
noise in a rubber band such that it would force intermediary stops?

Finally, isn't it true that a rubber band, when it's NOT being pulled or
pushed (a state of rest which I use to represents a finished print as
object), is its range still dynamic, or does it just have a length (range)?

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Where I think Roy, Martin, and myself are in agreement is that this
conversation will be greatly served when you clearly define just what it is
you maintain, even if you are not yet able to "prove" it. I think we all may
be more in agreement than it would appear, but that depends upon you. ;-)

Todd

PS, I good luck with your projects and peace to your family. I'm happy for
you you have more important things on your plate. But remember, you started
this. :-)