Digital BW, The Print

----- Original Message -----
From: "John Brownlow" <lists@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Thursday, March 28, 2002 11:28 AM
Subject: Re: [Digital BW] Dynamic Range Definitions and Print Tones


> On 3/28/02 1:22 PM, "Martin Wesley" <mwesley250@...> wrote:
>
(snip)

> >> 1. No analog systems are continuous at the quantum level.
> >
> > Hmmm. That is the same as saying there are no analog systems since the
very
> > concept of analog means continuous.
>
> Not at all. An analog system or device is one that represents data
variation
> by a measurable physical quality. You are arguing that that is continuous,
> not me.

John,

The definition I was working from includes continuous:

analog: 2 a : of, relating to, or being a mechanism in which data is
represented by continuously variable physical quantities
> >
> >> Not even the
> >> sun crossing the sky.
> >
> > The rotation of the earth occurs in small steps and not in a continuous
> > motion? An apple falls to the ground in distinct intervals? I know back
to
> > my rubber example but reality moves form state to state hitting all the
> > positions in between without breaks or step changes.
>
> I am just being pernickety. At the sub-atomic level it all falls apart. An
> electron does not trundle from A to B like a billiard ball. For this
reason,
> neither does the sun.

I don't know if that is a reasonable assumption but we are really getting
far a field.

I would need to call in Dad on this one. He is the theoretical physicist in
the family but he insists I would need to be 2 to 4 years into my physics
doctorate to be able to understand what he is talking about. I definately
agree with him.

> It is almost infinitely unlikely, but perfectly
> possible, that one day the sun will hop from one point of the sky to the
> other. That's the nature of quantum unpredictablity.

I can give you a good rate to insure you against lost you suffer in the
event that should occur. Say for $100 per month? <G>
>
> >> 2. A silver print or negative is not continuous at the granular level
in
> >> terms of its representation of the scene.
>
> > Not as a representation of the scene perhaps but... [SNIP]
>
> We are talking about it as a representation. That's the whole point of the
> discussion.

Well actually no. We got started over the claim that a Piezo print contains
more tones than a silver print without any reference to how the print was
made. I admit that this may be a dubious discussion. From a representational
point of view Photoshop and a good scanner or digital camera may allow you
to achieve a better tonal capture/compression than traditional photography
so that you can represent more real life tones in a print. However, you
could make that print from Photoshop to inkjet or onto silver paper in a
LightJet or by producing an interneg for silver printing. So the claim may
have some validity for digital B&W but I don't think it is true for a silver
vs. inkjet comparison.
>
(snip)
> >
> > Well you can control where those 256 bits fall within a tonal range and
if
> > you can do that, any tone is available to you even if you can only get a
> > finite number of them into a particular print. Think of it this way.
Within
> > the range, what density can't I reproduce in an inkjet print?
>
> You can map each of those 256 brightness values to any output value you
like
> but that doesn't make it a continuous tone image. There are still 256
> brightness levels in the output image with discrete steps in reflectance
> between them.
>
Agreed. But I think that by adding dither and varying droplet size you can
produce a continuous tone, perhaps not with 8 bit but with multiples of
8-bit. Can't back this up with hard fact though. Practically, a well made
inkjet print seems to convince my eye that it is continuous tone although
ones that are not well done have a very non-continuous look to them.

Martin