Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@y..., "gulstenek" <kevin@d...> wrote:
> 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 believe you are referring to me.  Thanks for reading it.
BTW, just eliminate confusion its Roy not Richard.

> 
> 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.  

Absolutely, true.  Imaging is certainly the example here of a non-time varying
signal that is amenable to the "dynamic range" concept.  The thing is you have to
be careful how to translate one system into the other.  Here's another way
to look at the issue that easily works in both systems.

Dynamic Range is a characterization how much bigger the maximum intensity is
from the minimum intensity of the system.  In sound that's the ratio of the loudest
to the quietest.  In an image that's the ratio of the brightest to the darkest.  
Austin's ratio is of the high contrast to the lowest contrast.  It just doesn't jive.

This is a link to some background material 
> (not definative but topical). http://www.prosig.com/signal-processing/

I read thru several articles, very audio oriented.

> 
> 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

Roy Harrington