Digital BW, The Print

on 3/24/02 6:27 PM, Martin Wesley wrote:

> I am afraid that we are probably the only ones wading through this and
> should go off list or hope for a chance to actually discuss in real time.
 
Please don't. This discussion will continue to rear it's head here until
it's finally put to bed. I agree it might not be everybody's taste, but you
are, in an oblique way, still discussing what is dynamic range and how it
may relate to BW prints.

If you guys do take it off list could you at least CC me your posts - I'm
interested.

Martin wrote:
>> I think that you are redefining dynamic
>> range in light of your electronics and digital background that are not
>> completely applicable to a paper print.

Austin Wrote: 
> Dynamic range IS dynamic range, period, what ever the application!  It is
> completely applicable.  As I've said, this is a point of confusion that has
> been around for some time, understanding the difference between density
> ratio values and dynamic range, and that they are not interchangeable terms.
> The term dynamic range is typically misused.  It is similar to the
> misunderstanding that because positive film has a wider density range, that
> it has a higher dynamic range, and it does not.  Negative film has more
> discernable tones than positive film, and yet it has a shorter density
> range.

After the last time this discussion occurred on list Austin and I continued
it off-list, and what I came to realize is that Austin does know this stuff
inside out but he does use the terminology differently than most Photoshop
authors. I don't know which is right, or if it just boils down to what is
common usage.

Austin's background is scanners and digital capture, and in that world,
where the data is written linearly, dynamic range is defined by the number
of discreet points of data. That's why I always thought he was confusing bit
depth with DR, because he speak of the number of tones, but he's not -
That's just how DR is considered in that world.

Austin, there was one point in our last conversation that you promised you'd
clear up for me but did not, perhaps you could do so now? You said two
things that seemed to contradict each other:

A) any DR can be defined by two bits of data. First off, why two bits and
not one. I'm assuming you were speaking to what you consider "range" when
you said that; If so, why not one bit of data: dmin-dmax? B) DR is defined
by the number of discreet steps of data. That seems in direct contradiction
to A.

Could you explain the relationship of A to B?

Thanks,
Todd