Re: SilverFast (negafix)

["Ernst Dinkla" <E.Dinkla@xxxxxxxxx>]

----- Original Message -----
From: "Paul D. DeRocco" <pderocco@ix.netcom.com>
To: <scan@leben.com>
Sent: Wednesday, March 13, 2002 7:56 PM
Subject: RE: SilverFast (negafix)


> I have trouble understanding why a negative should be
intrinsically more
> variable than a transparency, given that the latter had a
negative in it at
> one point, using chemistry that had way more constraints on it
(e.g., the
> ability to wash those dyes out) than any negative film.
>
> But most scanner software doesn't attempt to do anything more
with a
> negative than apply a fixed negative to postive transformation,
using curves
> built into the software. This just duplicates the sort of table
> interpolation calculations that a color management engine does
under control
> of an ICC profile. And using an ICC profile would allow
something like
> standard tools to be used to build such profiles. This may not
compensate
> for the lot-to-lot variability of negatives, but then neither
does anything
> else--except perhaps NegaFix, and people are saying that that
doesn't
> eliminate the need for tweaks, either.

The negative film has a more compressed character as a first step
to the final image on paper that will never have the contrast of
a slide. With the knowledge that only the positive paper print
would be viewed by eye they also did some other tricks that
resulted in an even more off colour negative. That off  colour is
then corrected in the print. As a total it is the right approach.
For scanning it is nice that there is some compression done
already. But if there never will be a conventional positive print
from that negative made it would be sensible to make a film that
has the compression but not the mask etc. Or make a slide film
that has more compression if it has to be scanned only.

The extra mask(s) + any difference in development that has more
influence on the compressed image colours may be the cause of the
variation I guess. And maybe that part of the process never was
considered that important because the other step after it would
compensate the variation.

Ernst



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