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[filmscanners] Re: Dynamic range

Laurie Solomon wrote:
> As interesting as this discussion may be and as important as it might be, I
> suggest that you two carry on this discussion as you propose in point (1) or
> otherwise via private emails until you either come to some common ground or
> to some conclusions.  At that point, it might be appropriate to let the list
> know what conclusions the two fo you mutually agree on and have come to
> accept.  I see little point in bickering among yourselves any more in
> public.  The other alternative of course is to move it to
> http://groups.yahoo.com/group/max-noise/ if there are more than just the two
> of you that are interested in the topic since that is were those who are
> interested in the topic and the debate can partake of the discussion without
> bothering everyone else with the trivia of the intramural back and forths.
> If Austin does not want to join that list or does not want to continue the
> debate with you in private, I suggest that you just forget about including
> him in the discussions and just preach to the choir who are willing to got
> to that list or carry on the discussion in private.

Hi Laurie,

I share your feeling of frustration and exhaustion of all the arguing
about this point.  This argument about dynamic range has gone on and on
on many different groups and many different times -- it's truly mind
boggling.  The technical descriptions of what's what seem to have fallen
on deaf ears.  Much as I believe that Julian's post is the most accurate
and thorough description of the situation, it seems to be fruitless in
terms of convincing anyone.

So, rather than continuing that trend, I'd like to appeal to what many
if not most people are familiar with and do every day.  That is, scanning
film, manipulating with Photoshop, and printing images.

Consider the current state-of-the-art scanning and printing that we
are all involved with.  The current crop of high quality pro/consumer
scanners are all about 14-bit depth.  That gives 16384 potential
gray levels.  The demand is obviously there for this bit depth
capability.  However, virtually everyone who wants the high bit
scanners is perfectly content with printing using only 8 bit
files -- i.e. 256 levels.  Going further, the printers themselves
don't print 256 levels.  Some of the best results these days are quadtone
inkjets.  That's 4 levels of gray ink plus of course the white of the
paper i.e. 5 levels total.  Each dot on the paper can be one of 5
possible gray values.  So, we have images going from 16384 levels
to 256 levels to 5 levels -- and we're all pretty happy with the
results.  So I ask you and anyone else is "number of levels" much
good at characterizing what's happened to the image on the way
from film to paper?

Now if Dynamic Range were "number of levels" we'd have the situation that
we're all spending big bucks for high dynamic range scanners and then on the
way to printing, first throwing away more that 98% of the dynamic range
in Photoshop and then throwing about another 98% of the dynamic range
in the printer.  That's throwing away a total of 99.97%  from film to
paper.  Obviously absurd.  Or was it that right at the end the dynamic
range mysteriously came back?  Are we all nuts wasting our money?
Is dynamic range just a worthless measurement?  What happened to the dynamic
range during all that?

This may not look like a proof of anything but ought to be a reason to spend
some more time thinking about it.  The only correct answer to all the
questions above is that dynamic range isn't defined as number of levels.

Please, think about it.


Roy Harrington
Black & White Photography Gallery

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