Digital BW, The Print

----- Original Message -----
From: "John Brownlow" <lists@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Sunday, March 24, 2002 7:51 PM
Subject: Re: [Digital BW] Dynamic Range


> On 3/24/02 mwesley250@... wrote:
>
> >Think of a rubber band. Let's say it is 2" long in it's relaxed state and
it
> >can be stretched to a length of 4" before it breaks. This is an analog
> >system and it can be any of an infinite number of lengths between 2" and
4",
> >the dynamic range of the length is 4:2 or 2. Just because your ruler only
> >has divisions of 0.1mm does not mean the length of the rubber band can
only
> >be in 0.1mm steps.
>
> your rubber band is not a signalling system

John,

True and a simplistic mechanical system.
>
> s/n ratios only make sense in the context of representational systems
>
In control systems and measuring devices too. In fact until digital
electronics came along, most of the control loops in a chemical plant
depended upon spring like actions identical to my rubber band.
>
> if your rubber band was somehow being stretched to represent a signal
> then it would indeed have a noise floor and s/n ratio

True.

This is where things have wandered off. The original statement I objected to
did not, in my opinion, have anything to do with dynamic range. Austin said
that an inkjet print contained more tones than a silver print. This is aside
from representing anything or looking at the entire loop of scene, camera,
scanner, computer, printer or any workflow you choose.

My argument is that you can achieve any tonal value you want between the
minimum and maximum value of the print medium with either process. Since the
prints themselves are analog, there are an infinite number of tones that can
be achieved with either. Like a slide on a guitar string. You can get an
infinite number of frequencies between any two points along that string.

As you say noise and s/n only apply to the conversion of information from
one form to another. They provide a measure of the likely accuracy of the
transfer. It does not tell you anything about the number of tones in the end
result. When you open the shutter you are exposing the film to a scene with
a minimum value, a maximum value and an infinite number of shades in
between. The negative then has its min, max and an infinite number of tones
in between and so on to the print. The noise and s/n of the system influence
how well the tones on the end result match the tones of the original scene
but they do not predict a finite number of tones in the print.

In the end I don't think the question makes any practical difference to the
printing process. However, the claims of more tones in inkjet prints keeps
surfacing every and I do not see any data to support this. Hence my
objection.

Martin