Digital BW, The Print

Hi Austin,

Well at least you did come thru with references.  Thank you. I've
read thru them all at least to find what was relevant.  There is a lot
of information.  My biggest disappointment though is that they are all
audio digital signal processing articles with maybe the exception of the
Osiris Manual.  I'm really not prepared nor do I think its appropriate to
argue this whole thing on an audio level.

I spent time on your original Higgin's book, looked at the formula, the diagram
and the derivation for audio.  I thought about interpreting the info for
imaging (particularly from the point of view: what we perceive) and came up 
with a way to use the formula for images.  I also looked at the way
you interpreted it.  Right or wrong I think we both have interpretations
that are at least mathematically reasonable.  From my point of
view, your way made less intuitive sense than mine, but I perserved and
tried to understand what the end result meant.  I.e.  could I conceptualize
the quality or property so defined.  Mine is certainly pretty simple (in fact
I think you believe its too simple).  But I've yet to really come up with a
feeling for yet except for maybe number of tones.  It seems several others
on the list are also trying to conceptualize it, too.

Anyway, given all that, I looked at a lot of the imaging literature and the
descriptions of dynamic range all seem to agree with my view.  Some may
be somewhat ambiguous but I've not seen anything clearly contradictory.
Scanner hardware specs all use the same terminology.  
I described in fair detail how to view DyR as an image passed thru various
stages, so I made a practical argument as well.  

So here we are.  You've pretty much blown off all the "experts" in imaging
saying they are not engineers and don't understand -- only audio experts
know what this is all about.

> 
> Dynamic range is never measured in density, it is measured in dB.

Minor question: If dynamic range is a measure of how many gray tones 
there are, how come its in dB and not just an integer.   Why doesn't
it just say there are 237 grays in this image??

Somehow, I'm never going to feel good about my image having 63dB
of dynamic range.  Maybe I can up it to 71dB and beat the other guy :)

  There is
> a reason for that, simply because dB shows how much is there, as opposed to
> density range which doesn't say a wit about what's in between.  Dynamic
> range is a property of the "discernability" of density.
> 
> > The staircase model seems so perfect
> > I'd like to keep pointing back to it.
> 
> Yeah, but your belief of what it represents is mistaken.  The bottom step is
> dMin, the top step is dMax and the number of steps is the dynamic range (and
> in the digital world, also the bit depth).  This probably got misinterpreted
> because someone, sometime, used a staircase example to try to describe
> dynamic range to someone else, who didn't quite understand it...etc.  Kind
> of like telephone.
> 
> Obviously you want to believe what you want to believe, and/or just don't
> want to understand what dynamic range really means.  I know you believe you
> understand it, but from what you cite, you don't.  You use references that
> don't understand it themselves, and when I cite references that are quite

Well, terminology aside.  Adams certainly had enough understanding of his
photography for me.  And the scanning book sure is more informative on
the ins and outs of scanning.

> technical, you either ignore them, or misinterpret them.  I know you can say
> that I am misinterpreting them...but I HAVE designed imaging equipment, and
> audio equipment, and subjected my self to PROFESSIONAL peer review.
> 
> You are obviously an excellent photographer, as I've visited your web site,
> and find your work to be outstanding.  Perhaps it might be useful if you
> stated what your background is that is applicable to this discussion.  You
> said you have "a couple of degrees in EE", but haven't said at all what your
> "field" is (or was), or if you've actually done any applicable design work,
> or used the concept of dynamic range in any of your work.

Not that it matters much, but BSEE MIT, MSEE Stanford, My field has been
mostly computer science.  Personally designed and personally written a ton of code.
I was the head technical person starting a company with 4 people and 
growing it to several thousand.  Not much in peer reviews, all the techie
people worked for me, sorry :).  Seriously, I worked in every aspect of computers
and what was connected to them.  Figuring out how systems worked and how
to make them work for you in lots of different fields is what I've always done.

You can probably claim more dynamic range usage in your specific area, 
but my diversity has served me well. 

> 
> You've never answered what is "dynamic" about YOUR belief in what dynamic
> range means.  I believe, there is nothing dynamic about what you believe
> dynamic range is, and I believe dynamic makes perfect sense when applied to
> what I say "dynamic range" is.

So you're asking how I think the English definition of "dynamic" is relevant to
the technical definition??  I thought we were talking about a technical
definition that was explicit and precise technically.  No?

Actually, the word I've equated "dynamic" to is "useful".  In ranges such as
exposure, Zones, density.  The useful part of those ranges is where the
image information is.  The part of the range is "dynamic", the parts outside
are dead, useless, have no image.  Hence "dynamic" rather than "dead".
Its just an English language analogy, but then that's all you asked for.

> 
> Austin

I guess we're pretty much at an impasse.  Too bad.  I think I found some
pretty useful ways to view the term "dynamic range" as images passed
thru various steps and what it meant.

Sorry about any grumpy tone to this. I'm frustrated as I'm sure you are.
I gotta go make some pictures.

Roy