Digital BW, The Print

----- Original Message -----
From: "Austin Franklin" <darkroom@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Saturday, March 30, 2002 8:24 AM
Subject: RE: [Digital BW] Is dynamic range more important than densityrange?


(snip)
>
> Whether noise is near 0 or not, density range and dynamic range are never
> the same, simply because their units of measurement are entirely
different.

But one may become of no practical interest in evaluating the system while
the other still is of use.



----- Original Message -----
From: "Austin Franklin" <darkroom@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Saturday, March 30, 2002 8:30 AM
Subject: RE: [Digital BW] Is dynamic range more important than density
range?


> > > Then, how do you "describe" the difference in number of tones?  That
is
> > not
> > > defined by density range.
> >
> > If the mumber of tones is infinite or higher than we can
> > differentiate then
> > the number of tones in not important.
>
> You're avoiding the question.  Because they are not discernable to YOU
does
> not mean they are not discernable.

If I believe the number is infinite or appears to the eye to be infinite
then comparing them has no meaning. I believe that this was my original
point that silver and inkjet were the same in this regard.

The fact that tones are more discernable to a densitometer than are
discernable to the human eye has no effect on the visual presentation of the
print. It is irrelevant for practical photography and print making.

> There are also prints that exist that
> have a number of tones that we can differentiate.  How do you "describe"
the
> difference in number of tones?  NOT with density range...but how?

Since you can make any print you want and pick what tones you what to use
you could choose to make a print with a specific number of tones. As in a
print of a step tablet. My understanding was that the discussion was about
the print mediums of inkjet vs. silver. No individual prints or that we were
discussing full range and tone prints that contain all the tones available
to each system
>
> You've also shifted the discussion from your original claim, and are now
> saying dynamic range isn't relevant because we can't see it.  The
> interesting part is, you don't know that we can't see it, and you can't
make
> the claim that we can't see it in EVERY image printed, now can you?
>
No, for the sake of ending the debate over infinite tones, I asked that we
consider the case where there are a finite number of tones and expressed my
opinion that if the number of tones is very high then dynamic range is no
longer of practical interest.


----- Original Message -----
From: "Austin Franklin" <darkroom@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Saturday, March 30, 2002 8:36 AM
Subject: RE: [Digital BW] Dynamic Range Definitions and Print Tones


(snip)
> >
> > As in continuous tone? <G>
>
> That doesn't make it continuous.  Continuous is merely a perception...so
> whether it "appears" continuous is solely based on the sensor used to
> perceive it.

Continuous is a mathematical function and not a mere perception.

(2 of a function : having the property that the absolute value of the
numerical difference between the value at a given point and the value at any
point in a neighborhood of the given point can be made as close to zero as
desired by choosing the neighborhood small enough)

Although only what we perceive is of any interest to us a photographers and
printers. If there are imperceptible changes, why would they effect the
quality of our prints.
>
> Neither chemical prints, or inkjet prints ARE in reality continuous tone.
> As I've pointed out, you would need a sheet of paper of infinite size to
> represent your definition of continuous tone (being entirely stepless),
and
> that does not exist.

If it is stepless any size paper will do.


----- Original Message -----
From: "Austin Franklin" <darkroom@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Saturday, March 30, 2002 8:52 AM
Subject: RE: [Digital BW] Dynamic Range Definitions and Print Tones


> > Okay I will add:
> >
> > From X-rite's "The Color Guide and Glossary"
> >
> > "Dynamic Range: An instrument's range of measurable values, from
> > the lowest
> > amount it can detect to the highest amount it can handle."
>
> Yeah, what's wrong with that?  It's exactly as I have said.  The lowest
> AMOUNT (not least amount mind you) it can detect IS the "smallest
> discernable signal".  Highest AMOUNT it can handle is still a bit dubious.

Nothing wrong with that for the dynamic range of a densitometer or other
measuring device. By "highest amount it can handle" I imagine they mean the
highest and still maintain their stated tolerance.
>
> As I've said, provenance is the equation, period ;-)

So it is okay not to have an equation in the definitions you like. You
objected to the lack of equations in all the others.
>
> > From CCD Direct:
> >
> > "The dynamic range is often represented as a log ratio of well
> > depth to the
> > readout noise in decibels. For example, a system with a well
> > depth of 45,000
> > electrons and a readout noise of 15 electrons would have a dynamic range
=
> > 20 log (45,000/15), or 69dB."
> >
> > http://www.ccddirect.com/online-store/scstore/dynamic.html
> >
> >
> >
> > You never did say what you thought of this last one which seems to be in
> > your field.
>
> It's fine, it includes noise, as it should, and the equation is correct...
> The RANGE is 45,000, and the noise is 15, and they divide range by
> noise...exactly as I have been saying every time...  A depth of 45,000
means
> a Max of 45,000 and a min of 0...
>
> I didn't comment on it because it's entirely correct, and fits everything
> I've been saying to a "T".
>
That's what I thought but wondered if you had missed it.
>
> > > Er, yes I did.  I gave you an example using 0.01D as the "noise".
> >
> > Hmmm. Somehow an example just doesn't satisfy like an experimental
value.
> > What if I say for example that the noise in a silver print is
> > 0.00000000000000001 dB can I use that? <G>
>
> If you want, I have no problem with you using ANY value, all I'm trying to
> get you to understand is chemical prints HAVE dynamic range.

Well at this point let's say I don't care unless the value of the noise is
large enough so that your DyR equation gives us a value that will allow me
to say one system makes a better print than another. If both have a finite
number of tones and we can visually see this in the prints then it would
seem that DyR is important. If we cannot distinguish a finite number of
tones visually, not with an instrument, then the DyR will not help us
evaluate the two.
>
> > I have no reason to believe that noise exists everywhere and I can't
take
> > that as a given.
>
> OK, but I can state unequivocally it does...at least in the physical
world.
> Noise doesn't exist in the number 1, but trying to measure 1", it does.
Can
> you name any physical property that doesn't have any noise?

Length has no noise. The measurement of length has noise. You continue to
confuse the measurement of something with the thing itself.
>
> > The noise you described earlier would be
> > variations within
> > a given paper base rather than the variation from brand-to-brand
> > and may be
> > so small as to push the results of your equation towards infinity.
>
> Source of noise isn't relevant to the dynamic range OF the print, the
> print's dynamic range is the print's dynamic range, irrespective of where
> the noise came from.  It is relevant to the dynamic range of the system
> though.

I keep offering to consider what the noise would be and how we could measure
it in order to determine the importance of using dynamic range in evaluating
prints mediums and you say the source of the noise is irrelevant? I begin to
suspect you are not certain that the noise can be determined or measured. I
am not interested in proving some theoretical idea at this point in the
discussion. Can you actually calculate the dynamic range of a print and is
that value of use? Are you really interested in doing this? Do you really
want to determine if a silver print or an inkjet print has more tones or
not?
>
> > Well I am a very practical engineer. Chemical process and project
> > engineering remember, so I want to know all those details.
>
> I am a very practical engineer too...I like to understand what it is I am
> trying to do here before getting into the details.  You and I haven't
worked
> out the basic concepts here, so the details aren't relevant.  Perhaps you
> are having trouble seeing this through the details?

If you cannot provide enough details to practically implement your ideas,
what is the point?
>
> > True but you need a meaningful value for the noise to do that.
>
> Yes you do.

Exactly. Until you do have a meaningful value what is the purpose of
comparing the DyR of a silver print to an inkjet print?
>
> > > > If you don't have the
> > > > values you
> > > > need to apply your dynamic range equation, what use is it?
> > >
> > > Having a "correct" value or not doesn't mean it doesn't exist!
> > >
> > No but lack of a correct value makes it of little practical use.
>
> Yeah, but I'm trying to convince you it even exists, not anything about
the
> practicality of it...that's a waste of time until you understand the
concept
> and it's existence!

I have already stated several times that I am willing to assume that your
concept is entirely correct and have tried to move on to look at what the
practical implications of using it would be.
>
(snip)
>
> BTW, do you have children?

No I got too old and missed my chance. I do have a 4 month old Scottie and a
3.5 month old Westie puppies at the moment to keep me busy.


----- Original Message -----
From: "Austin Franklin" <darkroom@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Saturday, March 30, 2002 8:56 AM
Subject: RE: [Digital BW] Is dynamic range more important than density
range?


> Hi Martin...
>
> > Remeber Plane Geometry? The Postulate that says that any line segment
> > contains an infinite number of points? A tone has no width so there is
no
> > limit on how many you have within a line segment on a tone curve.
>
> But measure those points on the line for me will you?  Get it?

That is the core. They are there whether you can measure them or not. There
existence is independent of our ability to measure them. For practical
purposes we are only interested in what we can measure but we must always
consider that our measurements only approximate what we are measuring.
>
> > > > What would that mean in terms of your dynamic range equation?
> > >
> > > Your minimum discernable signal is now the limits of your eye.
> >
> > Then shouldn't were be looking at the limit of our eyes and not
> > the prints?
>
> But that's you putting the limit on this!

Isn't that the whole point of the discussion? You stated that you could SEE
more tones in an inkjet print than you could SEE in a silver print.
>
> > And if the prints all exceed the discernable limit of our eyes
> > wouldn't the
> > factor of interest then be the density range?
>
> Not necessarily.  How do you know you have a full set of tones?  Because
you
> may reach the limits of the eye in one "range", doesn't mean it does
across
> the entire print...hence posterizing ;-)

If it is posterized then it has failed the test to successfully reproduce a
continuous tone. I might note here that while posterization is often a
problem in inkjet printing it is not a problem encountered in silver
printing. Would that fact be an indication as to the relative number of
tones available in each medium.
>
> > > > Is that because of the quality of the materials or how they were
used?
> > >
> > > Could be either, and may be something else...and I believe that's
image
> > > dependant.
> >
> > As in negative or as in the actual scene?
>
> Not quite sure what you mean here...

When you say image dependent are you referring to the image on your negative
or the actual scene the negative tried to captured?

Martin

From: "Austin Franklin" <darkroom@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Sunday, March 31, 2002 8:55 AM
Subject: RE: For Austin Re: [Digital BW] Is dynamic range more important
than density range?


> > I am not
> > sure we are doing much more than rebutting each others statements
> > endlessly
> > at this point.
>
> I do believe you're right.  You and I haven't really brought anything new
to
> our "arguments", per se, but I also believe other very interesting points
> have been brought throughout the discussion.

Austin,

At this point I think I will just pick a couple of things that appear to
have a different slant and let the rest go as I am afraid we are getting
repetitive. Perhaps to continue we need to simple make some fresh post.
Continuing these individual threads to such great length seems to lose a
great deal of the continuity of thought. I have read all your replies so I
am not ignoring what you wrote.

>
>
> > >
> > No, for the sake of ending the debate over infinite tones, I asked that
we
> > consider the case where there are a finite number of tones and
> > expressed my
> > opinion that if the number of tones is very high then dynamic range is
no
> > longer of practical interest.
>
> But now you're putting a qualifier on this.  The original statement was
that
> density range and dynamic range are the same, and they are not.  Whether
you
> can perceive it with your eyes doesn't mean it doesn't exist.  It really
is
> two entirely separate issues.

The issue was number of tones and we got stuck over the definition of
dynamic range. In photography, rightly or wrongly, dynamic range has
frequently been defined as the density range which is an expression of the
reflectance ratio. The one thing I would ask we keep in mind is that this is
a useful relationship regardless of what we choose to call it. Your equation
defines a different relationship but shares Dmin and Dmax as key values.
>
> There is also another issue that hasn't been brought up.  If the eye can
see
> 100 tones, what EXACTLY does that mean, with regard to a print.  Here are
> two extremes.  We have a full tonal range from dMin to dMax, where dMin
and
> dMax are at the limits of the printing process.  Second print, has 100
> tones, but they lie in a VERY limited range of the overall ability of the
> printing system...the dMin and dMax of the actual print are much much
> smaller than the dMin and dMax of the ability of the printing system can
> achieve.  What do we see?  I believe we CAN see 100 tones, if in the right
> light...simply because of how our eyes work.  Now, I honestly don't know
the
> answer to it, but the point is, if what I am theorizing is true, the
dynamic
> range becomes more significant, than if we just assume 100 tones across
the
> entire printing range is sufficient...  Unnastan?

I am not sure but you may very well be right. By varying the lighting you
are varying the amount of reflected light that reaches our eyes. Under a
given lighting situation our ability to discern between two similar tones
has a limit. If we start at one end of the scale where we can first discern
a tone as different and proceed toward the other end of the scale until we
can no longer discern a difference there is a finite set of 99 tone pairs.
If when we reach that limit we have also just reached the other end of the
tonal range of the print then it is matched to our eyes and those viewing
conditions and is perhaps very appealing visually. If we reach the end of
those 99 tone pairs and have not reached the other limit of the prints tonal
range then we can't see the detail and the print does not look so good or
appears to be missing tones. Also if we reach the end of the print's range
and have not reached 99 tone pairs the print may seem flat and dull.

This would lead to the idea that under one set of viewing conditions an
inkjet print matches the range of our eyes and in another set of viewing
conditions a silver print matches the range of our eyes. Reverse viewing
conditions and the silver print appears to lack shadow detail and the inkjet
print seems to have weak blacks looks washed out. This seems likely to be
true but I don't know what we do with the information other than to keep it
in mind.

I suspect that in normal lighting the 1.4 to 1.6 Dmax of inkjet is below our
threshold and the 2.2 to 2.4 of silver exceeds it.

Then in terms of a system made up of the print, our eyes and the viewing
conditions your dynamic range equation becomes more interesting. The
difficulty is that our prints need to look good in a reasonably wide range
of viewing conditions and to a reasonably wide ranges of eyes (and I bet
there is a lot of variation there!)
>
>
> That's the first I've read of that!  If that's the case, then we can move
on
> past that point...perhaps you have, and I just didn't know it yet ;-)
I'll
> accept your premise that you accept my premise...but I'm not going back
and
> re-writing the top part of this post in light of that...all right, may be
> I'll skim it ;-)

Well like I said, all these long threads (posted out of sequence courtesy of
Yahoo) has lead to a lot of confusion.
>
> It appears that you're at the "is it useful" and "how do we measure it"
> stage, right?  I believe I've said yes, and shows why it may be to the
> useful question, and I believe I've given an example in a post to Todd on
> how to measure it...but I also believe that measuring it may not be
useful,
> the fact that you can visually distinguish the dynamic range of two prints
> serves the concept well.

The problem is that visually distinguishing it without being able to put
some numerical values to it seems awfully subjective and open to confusion.
>
> > No I got too old and missed my chance. I do have a 4 month old
> > Scottie and a
> > 3.5 month old Westie puppies at the moment to keep me busy.
>
> We have Airedales (as well as children) ;-)

Airedales are great! Kids, ummm..... ;-)
>
> BTW, I just thought of a very good dynamic range comparison.  A Polaroid
> print with a chemical print.  Also, positive film vs negative film.
>
> It is, I believe, well known that positive film has a lower dynamic range
> (less tones) than negative film.  I know I have noticed the difference,
and
> yes, I've shot the same scene.

I keep meaning to give their P/N film a try but I have no experience with
it. Don't you have to use a different ASA for P or N exposure?
>
> Don't confuse exposure latitude and density
> range here with dynamic range, a lot of people do ;-)

Oh I would never do that.

Best,
Martin