Digital BW, The Print

No offense Austin, but you really snipped out all my relevant points and
didn't answer much concretely.

I guess you're getting tired? ;-)

My main point was that for a formula that you suggests indicates the number
of tones present in a print, based on sampling as few as three tones, may
not yield a different number for each of two prints, even though one print
contains three tones and one contains 1000.

And I never spoke to a system in my post, precisely because I'm probing to
see if DyR holds up as useful (in the way you suggest = describing the
number of tones present) specifically for an existing print. I have no doubt
that DyR is useful for describing some aspects of a system's potential.

You also did not speak to my premise that I think that a calculation of
tones from DyR is only possible if linearity is assumed, which is not
something I would take for granted in a silver print.

Todd

>> So you've sampled three tones, referred to as: min, max, and test (or min
>> discernable, or noise). Let's assume this print was comprised of
>> ONLY these
>> three tones. You could calculate a very high DyR from these three tones,
>> implying the print has many intermediary tones, which it does not, no?
> 
> You need to separate the dynamic range of a particular image from the
> dynamic range achievable from the "system".  They are different.
> 
>> Really? First off I wasn't aware of that, when was that distinction made?
> 
> Martin said that chemical prints don't have dynamic range since you can't
> measure any discernment in tones, he claims they are infinitely continuous.
> 
>> Second, so are you saying the two require different testing
>> methodologies to
>> determine DyR? That's the first you've said of THAT.
> 
> A single test methodology can be arrived at.
> 
>>>> 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...
>> 
>> Okay, lets explore this.
> 
> It IS relevant in that it bounds the "largest" signal, but you can have a
> lower "largest" signal, and have a higher dynamic range.  That's why I said
> it isn't relevant.  Relevant really isn't the right word perhaps.
> 
>>>> 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.
>> 
>> Well it's not a given in every case, but we know MOST people out here are
>> Piezo printing from 8-bit, 256 shade files, and I trust you agree most
>> continuous tone negative films are EASILY *capable* of containing
>> more tones
>> than that. Tell me you don't disagree with that!
> 
> That's negative, not print.
> 
>>>> 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.
>> 
>> Okay, how many tones are in a print with a DyR of 25db? 10, 100, 1000?
> 
> 25 = 10log10((dMax - dMin) / sds)
> 
> Now, I claim that ((dMax - dMin) / sds) ARE the number of tones, so it
> doesn't matter what those three values are ;-)
> 
> So, 25 = 10log10X, makes X 310.
> 
>> Is it possible to measure a DyR of a print that contains less
>> than that many
>> tones?, Say a print with paper white with a 95% reflectance, a
>> dmax of 2.2,
>> a min discernable value of .1, and 10 solid shades of gray within the DnR?
> 
> You can always measure the dynamic range of one print...or the system.
> Different tests though.
> 
>>> P.S.  Please keep it short if you could...
>> 
>> I tried...
> 
> Hum ;-)
> 
> Regards,
> 
> Austin