Digital BW, The Print

> Earlier in the thread you have said (I'm paraphrasing) that the dynamic
> range of a print is an expression of how many tones that print contains.

Basically correct.

> I don't see how the simple test you suggest, which only differs from the
> more common test for dynamic range (or what you call density
> range) is just
> the additional step of measuring the variance across your test patch.

Exactly.  Since you can only discern by that value, that gives you the
minimum discernable value.  How it differs is quite simple.  Density range
does NOT take this into consideration at all.  It is merely a range between
two static values.  Dynamic range is how many discernable values you get
across that range.  Case in point is you can have a print with a high
density range, pure black on a pure white background, but it has no dynamic
range...no tones in between.

> I
> don't see how that information tells you how many tones are in the print.

You can only discern what you can discern, and anything that can't be
discerned is the same.


> This would seem to be a case where, as you've said before, only 2 bits of
> info is needed to establish dynamic range, no?

No, only two bits are needed to represent the DENSITY range.

> But this then could suggest
> the material is capable of a huge dynamic range, when in fact only three
> tones are present.

No, huge density range, but very low dynamic range.

> Furthermore, what does it say about a scenario where ones printer/workflow
> happens to produce a certain granularity/banding/mottling/artifacting
> precisely in the tonal region of your test patch, but nowhere else; or
> worse, the converse, everywhere but your patch?

It's merely an example.  You can quantify your system any way you want.
Those details are not relevant to the concepts involved that are trying to
be discussed here.

> And what of all this inkjet artifacting?

We aren't talking about inkjet prints in this example...only chemical
prints.

> Furthermore, I agree that there needs to be some term to
> distinguish between
> a litho-like substance, and a continuous tone substance, where
> the two could
> conceivably have the same density range, while one is capable of far more
> shades in between. But I wonder now if dynamic range IS that descriptor,

It is.

> when in fact you could measure a three toned medium and presume it to have
> the same number of tones and the continuous tone item, based upon
> that test
> and calculation. So, at best dynamic range can provide a
> predictor of what a
> medium is capable of, but it assumes a complete and linear set of tones
> between the ends, which may or may not be so; at worst it could
> mislead one
> wildly.

Not at all.  Dynamic range can be measured/calculated as precisely as you
like.  It's like measuring the width of a 4 x 8 sheet of plywood.  You can
just say it's 4' wide, or you can take a measurement every 1' or every 1" or
over any distance you want...  I'm just showing a measurement technique
here...there is nothing about dynamic range, per se, in this plywood
example.

> I need to explore this subject of linearity more fully as it pertains to
> dynamic range. For instance, a print with an expansion of highlights and
> contraction of shadows (= high contrast) will contain fewer tones than the
> material is capable of, but your measure of dynamic range will
> not indicate
> that has occurred. So, is dynamic range a measure of the number
> of tones an
> item contains, or a measure of what the material is capable of if perfect
> linearity is present?

It entirely depends on what you are measuring and how you measure it.

> This has me wonder why you assume a Piezo print to have greater dynamic
> range than a silver print given these considerations:

Because I have printed the exact same negative on both, and the Piezo print
had more tones visible to the eye.

> A) We know a well handled glossy fiber print is capable of a
> greater density
> range than Piezo.

Which is not really relevant to dynamic range...

> B) We know the source material of a silver print (negative) is capapble of
> more tones (millions? billions?) than the source material for an inkjet
> print (256? 65,000?).

I don't believe we know that.

> C) Noise can go either way, depending on which papers are used in each
> respective system, and other workflow considerations.

Absolutely.

> I'm trying to get my head around my sense that the approach you
> advocate for
> determining the dynamic range of a print is only marginally more
> informative
> than the approach to determining density range (which is fine, you didn't
> invent the formula <G>);

But density range only tells you the relative distance between the
endpoints, and as we have discussed in the past, can be represented with
only two bits...and as the simple equation for density range shows, it
merely is (dMax - dMin) and is a static measurement.

> that measuring the dynamic range of a print still
> doesn't tell you how many tones it contains;

It certainly does, as defined by the equation for dynamic range ((dMax -
dMin) / smallest discernable value).  Note, it has an additional variable in
the equation beyond what density range does.  The dynamic range of a
chemical print certainly can be done as a range.  You can add any complexity
to it you want...but it doesn't change the basic concept.

> that I see no logic that a
> Piezo print is any more capable of greater dynamic range than
> silver,

It doesn't have logic associated with it, it's simply observation.

> I told you this would be noisy/rambling. ;-)

You had a respectable dynamic range here ;-)

> Your thoughts please.

Anything else?

Regards,

Austin

P.S.  Please keep it short if you could...