Digital BW, The Print

Richard-

I really enjoyed your previous post on the subject.  It was a well reasoned discussion 
and broadened the perspective of the discussion.  Thanks for the effort.

I do have a couple of points on the comments below.  Austin's formula (and slight 
variations thereof) is used extensively in digital signal processing, and I am famialiar 
with it in that context ( my EE background).  The fomula is valid for signals that are 
not time variant as well as signals that are.  This is a link to some background material 
(not definative but topical). http://www.prosig.com/signal-processing/

Is Austin's definition the only appropriate one?  No.
Do people use dynamic range to mean density range?  Yes
Is that a valid use of the term?  I think so.
Is the formula valid outside of signal processing or describing systems? Not sure.

It seems wrong to leave the impression that Austin's position, although apparently 
intractable, is without merit.

Kevin Gulstene

--- In DigitalBlackandWhiteThePrint@y..., "royvharrington" <roy@h...> wrote:
> --- In DigitalBlackandWhiteThePrint@y..., "Austin Franklin" <darkroom@i...> 
wrote:
> > 
> > What are these "taped and printed discussions of dynamic range as it relates
> > to prints", aside from discussions posted on a web page, or in news groups
> > on the Internet?
> > 
> > BTW, I do understand that people have confused the term dynamic range when
> > they mean density range, for what ever historical reason...probably because
> > those doing it didn't really know what dynamic range was.  It is very
> > similar to the misuse of the term resolution when talking about computer
> > monitors (or digital cameras ;-).
> > 
> > Austin
> 
> Austin,
> 
> You've pushed you idea on dynamic range for imaging, time and time again.  Many
> people have argued with you.  I personally have gone to the library to look at
> your reference book by "Higgins".  First of all I'd like to point out that the
> formula and the diagrams you have spoken about are under a paragraph
> heading:   1.4.1  DYNAMIC RANGE EXAMPLE: ANALOG VS. DIGITAL AUDIO.
> The last word AUDIO is key.  You've claim to have 25 years of experience in
> AUDIO, fine.   You've claimed to have taken this formula, plugged in density,
> and defined dynamic range for imaging.  I tried several times to point out that
> it was at least possible to plug in density to the formula in different ways.
> You declined to admit that, saying there wasn't any interpretation, mapping,
> or logic, involved in going from the audio formula to imaging.  
> 
> Well, bottom line is you're mistaken, incorrect, misinformed or whatever you 
want
> to call it.  I don't expect or even recommend that you believe me.  You've got
> to investigate, research, and learn more about the Imaging World and figure it
> out for yourself.  I'd be glad to help point you in the right direction but you've
> got to do it yourself.  
> 
> Here's a couple of hints:
> The formula in Higgins book is about audio, explicitly showing the waveform
> nature of sound.   The signal diagram shows what to measure with a wave.
> Imaging is very different, when we talk about light intensity, or film density
> there are no waves.  They are direct measured values that can be perceived
> as constant values.  Your interpretation has made density into a waveform
> property which it is not.
> 
> Get away from the audio books, jettison the audio baggage.  Read some imaging
> books.  Here's a nice one:
> Read World Scanning and Halftones by Blatner, Fleishman and Roth.
>  -- page 13  direct quote
>   "Dynamic Range" expresses how broad a range of tonal values a scanner can
>   capture; this is similar to the photographic measure of "density".
>  -- page 14  direct quote
>    ... compare bit depth and dynamic range to a staircase: the dynamic range
>    describes the height of the staircase and the bit depth describes the
>    number of steps from the bottom to the top.
> Read Ansel Adams: The Negative
> Read the kodak website -- search for dynamic range.
> 
> Whether you like it or not dynamic range is well used in imaging and your 
> interpretation doesn't agree with the anyone else.   If you really like your function
> call it Austin's Cool Range Formula, and I'm sure we'd all be happy to let you
> own it.
> 
> I am sorry to be harsh about it, but I really think the aruments have
> become a disservice to the group.
> 
> Regards,
> Roy