Digital BW, The Print

> Austin,
>
> They are not my explanations they are the commonly accepted
> definitions by a
> wide range of people in many fields.

Martin,

Commonly accepted by whom?  Merriam Webster, magazines, etc. are hardly good
sources for technical definitions.  As I've said, the definitions you cited,
with the exception of a couple of them, require interpretation of ambiguous
terms.  They are NOT wrong, just open to (mis)interpretation.  Specifically
two terms used, smallest and largest (or what ever words were used).  I have
shown VERY CLEARLY what is meant by smallest and largest when used with
respect to dynamic range, as defined by a very definitive source.

> 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.

> Dynamic range is a ratio but subtracting log values is
> mathematically the same as taking the ratio. I don't see the need to
> reinvent the math either.

Me either, and I certainly am not "reinventing" math.  Just because two
"measurements" are expressed in log form does NOT mean they are the same.
Dynamic range stands in and of it self as ONE log10 number.  It is expressed
in dB.  Density range requires TWO log10 values, dMin and dMax.  Density
values are NOT expressed in any "scale" simply because they are relative
unto themselves.

> > As has been shown, you can have a very high density range (a high black
> > value on a very white paper, with no intermediate tones) and that has a
> very
> > LOW dynamic range, because there are no tones in-between.
> Don't let this
> > simple concept slip by...it's important.
>
> Where in the definitions was this stated?

What's "this" that you are questioning?  The measurement for density range
is clear, dMax - dMin.  The measurement for dynamic range is clearly defined
by the dynamic range equation.  Here, I'll apply some simple numbers to
this:

dMax = 1.8
dMin = .2

Density Range (dRange) = 1.6

Easy, right?

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.

The dynamic range is based on the largest ATTAINABLE signal for the medium,
not the largest for a single print.  You certainly could just print the
blackest black you could, and get it from that, not too tough.  Let's say it
was 1.8...for sake of argument.

The smallest discernable signal isn't dMin, since we could possibly be able
to "discern" in .01 density value steps...  and without knowing what the
minimum discernable signal is, we don't know what the dynamic range is, by
definition.

Let's say our smallest discernable signal was 0.01 density value (which is
hardly far fetched, and actually a reasonable number).  The dynamic range
would be 10log10((1.8-0.2)/.01) or 22dB.  Note that even in Bells, 2.2 is
not the same as 1.6.  Of course there happens to be a value for the smallest
discernable signal that would make dynamic range and density range the
same...but that's the same as saying a clock is right twice a day...it's
purely by happenstance.

> 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.


Austin