Digital BW, The Print

> If we start from the dictionary definition and try to
> move to paper prints selecting the meaningful or usable min and
> max as seems
> appropriate to that system.

But the equation for dynamic range does not allow YOU to select the
"meaningful" definition of smallest and largest as YOU understand them.
They are defined by the equation.

> > > I do not see the need to
> > > reinvent these
> > > meanings.
> >
> > Me either, and clarifying ambiguous terminology is hardly reinventing
> > anything.  I have merely cited the clarifications from reliable sources.
> > You have not attempted at all to cite any clarification to the
> terms that
> > are in question.
>
> For the most part I feel you are simply substituting synonyms.

They you are missing the entire concept.  What I have shown, quite clearly,
is that there are AMBIGUOUS definitions of both largest and smallest.  I
have also shown what the two ambiguous definitions are.

> The point
> where we collide is over "discernable."

But it's clearly defined by the equation and what dynamic range is there to
measure.  As I've said time and time again, you are arguing over a very
clear concept/definition/equation that I did not come up with.  I am merely
trying to get you to understand what it really is, and how your
understanding of it is flawed.  Unfortunately, for what ever reason I do not
know, it isn't working.

> I agree with this as part of the
> process of determining the min and max.

I don't follow you there.

> You move on into the idea of
> "discernable difference" over the entire tonal range and I think that this
> is not covered by the general concept of dynamic.

Well, then what do YOU believe is "dynamic" in dynamic range?  That is a
very important question.

> "Discernable difference"
> is very important when you are talking about systems where the input and
> output are changing with time

Time has nothing to do with it.  You do not need time to discern change, but
you do need change to discern time (off topic, but it's true anyway).  Two
things can have a discernable difference at the exact same time!

> I do not see how you can directly "measure" the
> dynamic range of a print. Perhaps in electronics you can.

Very simply.  Print a completely solid tone, with as minimum detectable
difference in density in the original as possible.  Print the darkest tone
you can.  Measure the darkest tone, measure the paper, then take multiple
measurements of the "patch" of your "test" tone.  The variance across the
test tone is your noise, and yes, I know, you have to account for the
original variances, as well as possible variances caused by the lense...but
none the less, it does give you a basis for noise.  You get the "largest
signal" in the dynamic range equation by your dMax - dMin, and you get your
"smallest discernable signal" from the variance in your "patch".  There you
have it.

> Density is a log of the
> inverse of
> a percentage, the reflectance, so it is all unitless.

He he, I'll remind you at a later date that you said that ;-)  It's also
unitless since it's only a relative number...and units don't matter.

> Back to the general definition which says the dynamic range is a ratio of
> the min and max.

As I've said countless times, min and max WHAT?  What does min and max mean?
They are incomplete terms.

 This does not seem to account for the values in
> between or
> they assumed a continuously variable system.

Min and Max does if you take max to mean the maximum signal and min to mean
the minimum discernable signal ;-)

> > What's the dynamic range?  Well, we don't know what the smallest
> discernable
> > signal is, now do we?  Nor do we really know the largest that the
> > paper/system can attain either.  This makes for a quandary.
>
> Not really because you are interested in the meaningful or useful values
> which may simply be the only the values you do know.

Sorry, I have no idea what you mean by that...

> I agree that you may be able to discern a change of 0.01 density
> near Dmin.
> The problem is that as you approach Dmax the density change you
> can discern
> decreases.

You're right, but only if you're above 3!!!  It's also not relevant to the
discussion, but is a noted point.

> The discernable difference is not a constant in this
> system which
> is why I object to using this in a dynamic range calculation for this
> system.

That's the first you've said that!  But...as I said, your claim is only good
for density values above 3, below 3, they are quite constant...and since
this IS a B&W list...and as we all know, B&W doesn't go above 2...I think
we're safe ;-)

> Do you see what is happening here?

Yes, and it doesn't matter.

> From your earlier diagram you indicated
> that the discernable difference was constant across the entire range. That
> is not the case here.

Well, it is the case, but even if it weren't, it's not relevant.  Did you
ever take Differential Equations?

> > > Dynamic range tells you nothing
> > > about the number of intermediate values.
> >
> > That's what you claim, and I keep telling you, you are mistaken.
> >
> > It really would help if YOU provide an EQUATION, with appropriate
> > definitions of terms used in the equation (as I have done), NOT some
> > ambiguous verbiage that is open to interpretation.
>
> I believe I did. From the definition the dynamic range is the ratio of the
> maximum divided by the minimum.

That's NOT an equation.  AND maximum and minimum are left undefined.

> Dynamic Range of the Reflectance = (maximum reflectance of the brightest
> visually discernable white)/(minimum reflectance of the darkest visually
> discernable black)

Yeah, but that's wrong.  You have just given an equation for DENSITY range,
not dynamic range.

> My thought is that the dynamic range of a print may not be a particularly
> useful expression for us. The simple range or knowing the lightest and
> darkest shades of gray of a medium are what is of importance to
> us.

But it is so obvious that some images may have NO tones between black and
white, and some may have a LOT of tones between black and white.  That is
why dynamic range IS important.

> We also
> tend to overly focus on getting the deepest black where in
> reality you gain
> more by increasing the brightness white.

I very much so agree with that!

> I understand that you are trying to give us an expression that says
> something about the number of discernable tones that a media or system can
> create but I don't think that this can be done here because I do not see
> that there are a finite number of tones.

And I do see a finite number of tones, or at least a "range" of the number
of tones.  I can certainly say one has more or less than another!  I have
done the same print that has very bad tonality, there aren't many
discernable tones, and I have re-printed the exact same image and managed to
get a heck of a lot more tones out of that same image...via development
time/exposure.  Similarly with film, I have film that has the blacks so
blocked up, and some that has them nice and open...and that was based on
development/exposure too ;-)  Dynamic range is VERY important to me, as I
want full tonality in my specific prints.  Density range isn't as important
to me, for reasons that have been mentioned by you and others.

You seem to be shifting a bit here...more to an argument that dynamic range,
what ever we believe it is, isn't really that important...  Just a note.

Regards,

Austin