[filmscanners] RE: Density vs Dynamic range

["Austin Franklin" <darkroom@ix.netcom.com>]

Hi Julian,

> > > No!!!!!   I don't!!!!!  Please read.  I say it is "usually"
> determined by
> > > noise, because noise is what USUALLY determines the smallest possible
> > > signal.  WHat  I actually say is dynamic range is based on
> > > largest possible
> > > signal and smallest possible signal.  I thought that was pretty
> > > straightforward.  Sheesh.
> >
> >OK, your clarification straightened me out...that your belief is
> still not
> >right...darn, I thought we were getting somewhere ;-)
>
> This makes it pretty hard to ever convince you of anything!

You, or anyone else, can convince me of many things, just not to do with
dynamic range.  It's like trying to convince me my Audi is a Ford.  It
isn't.

> However, you
> have agreed that you were wrong about what I said the first time.
>  I didn't
> give you a clarification, I just repeated what I said the first time.  So
> this little milestone illustrates that you are actually capable of making
> an error in interpretation

I would hardly call YOU using a different interpretation of a term...a term
that has ambiguous meanings, an "error in interpretation".  YOU merely,
finally, defined YOUR interpretation of that ambiguous term, which I believe
is wrong!  I was merely giving YOU the benefit of the doubt, as the
interpretation I was using for it would have made your statement correct.

> - at least once in your life.  Can you concede
> that it is therefore POSSIBLE that it might have happened another
> time?!!

It has happened many times, just not here, and not with this subject.  I
HAVE defined my terms clearly.  YOU have not.  Until you do, you are leaving
your ambiguous terms up for mis-interpretation.

> If yes, that there is just the tiniest chance, a 'one grain of
> sand amongst the sands of all the beaches of the world' chance, that you
> have an incorrect interpretation of what dynamic range is?!

Nope.  In fact, as my last post indicated YOU now are saying the exact same
thing I am, even by your equations and results which are NOT open to
interpretation.  You, of course, FAIL to address that.

> ******************************************************
> The dynamic range is NOT a resolution definition, it is a signal range
> definition.
> ******************************************************

Perhaps you can answer the following:

1) How, in your opinion, do you determine the "resolution" of an analog
signal, such that you get the optimum amount of information, and only valid
information, from the signal?  Please don't play semantical games.

2) How you would determine how many "bits" you need to again, capture the
optimum amount of signal information, and only valid signal information,
from an analog signal?

It's just so simply obvious to me (and to a whole cast of other people who
design electronics) that DR absolutely defines the useful resolution can be
used.  Funny, how EVERY analog to digital system, audio and scanner, ALL are
designed so that their resolution is EXACTLY equal to the noise!  Funny how
that is.  Since resolving to less than that, give you no more valid
information, and resolving to more than that loses information.  Hum.

>
> >So, you are saying that my reference material is entirely
> incorrect?  I KNOW
> >that isn't the case.
>
> Everything I have seen that you have quoted from a book I agree with.  But
> what you show from the books is NOT what you use yourself!

Wrong.  What I shoe from the books is EXACTLY what I have been using.

> You change the
> meaning of the numerator to derive a new formula.  And you use noise
> instead of "min discernable signal" because they nearly are
> always the same
> thing, but from a definition point of view, they are NOT the same.

I haven't changed the meaning of anything, and the diagram I provided
CLEARLY shows that "min discernable signal" and "noise" ARE the same thing
IN THE CASE WE ARE USING THEM, but you conveniently seem to ignore that
reference, as if it didn't exist.

Also, I HAVE agreed, and again YOU CONVENIENTLY IGNORE, that noise and
minimum discernable signal MAY NOT BE THE SAME THING in certain cases, and
that their meaning IS different, BUT NOT IN THE CASE OF A SCANNER CCD
OUTPUT.  Again, FOR OUR PURPOSES, THEY ARE THE SAME THING.

> Please
> think about this.    If a reference shows "maximum signal" or
> words to that
> effect on the top of the equation, it means what is says,
> "maximum signal",
> NOT ("maximum signal" - "minimum signal").

Well, if an equation uses the word "largest" and THEN provides a diagram
that shows that largest is the range between the maximum signal level and
the minimum signal level, then it OBVIOUSLY largest = (maximum signal
level - minimum signal level).

> Pleeeeeease show where each of
> your references state that the top of the equation is what you call
> "absolute range".  And please show references that use your
> actual formula.

Your semantical games aside, I have CLEARLY shown that, in the referenced
diagram I scanned from one of my reference book.  Either you are simply
ignoring the diagram, or you really don't understand it, or you're playing
games.

> > > Once again, if you want me to describe such a box where the "smallest
> > > discernable signal" is NOT determined by noise, just say so .
> >
> >But that would be a mis-use of terminology.  Again, for the 100th time,
> >"smallest signal level" is NOT the same as "smallest discernable signal".
> >"Smallest discernable signal" IS noise, and as my references have defined
> >it.
>
> OK here's an example.  It is a simple box that has a smallest discernable
> signal which is different from the noise signal.

It doesn't matter, as we have said, and I agree to, the fact that smallest
discernable signal and noise are NOT the same thing in all cases...BUT,
AGAIN, IN THE CASE WE ARE DISCUSSING, THEY ARE THE EXACT SAME THING.

<snip>

Your example does not have anything to do with the discussion at hand, which
is SCANNERS.  You example is for a non-linear system, which is NOT what we
are discussing.  For a scanner, which is a linear system, the DR absolutely
defines the resolution of the system.

<snip again>

> Julian's method
> ******************
> First, remove any DC offset at the output. There are none, so that is ok.
>
> Then... number of levels available at output
>          = max / noise
>          = 8.6V/1mV (because 8.6 V is the MAX VALUE of the output, it is
> not an "absolute range", it is the max value because that is what this box
> saturates at ---- 8.6V (corresponding to a 10V input)
>          = 8,600.
>
> Austin's method
> ******************
> Substitute the figures relevant to the output in Austin's formula:
>
> Austin's number = (max - min)/noise
>          = (max-noise)/noise     [here]
>          = 8,599/1
>          = 8,599

I am very sorry to say, but you are playing games.  I have CLEARLY stated
that you are using the equation incorrectly, and you chose to ignore that.
That is dishonest.

The CORRECT use of the equation is:

                = (max-MIN)/noise
                = (8,600-0)/1
                = 8,600

Sorry, Julian, I can not continue this conversation with you.  What I have
said is entirely correct, and you seem to have a problem handling that, and
need to IGNORE the correct use of terms and equation, and that in dishonest
and makes your analysis not credible.

I am not even going to waste my time reading the rest of what you wrote.  It
is PLAINLY clear that everything I have said is ENTIRELY correct, and YOU
NOW AGREE with it, as what I have said gives the EXACT same results as what
you are saying, it's just that you won't admit that, and need to modify my
statements to somehow show I am wrong, when I am not.

I HAVE CLEARLY DEFINED MY TERMS, SHOWED YOU HOW TO USE THE EQUATION
CORRECTLY AND YOU IGNORE IT.

Please don't bother answering any of my questions, or responding to this
post.  You have unfortunately shown that you have no intention of being
"honest" in this discussion.  I can only guess so that you do not come out
as having been wrong about what I've been saying...since it is not obvious
that your answers agree with mine, given the same numbers.  There is NO use
in continuing this.

Austin

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