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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.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com

> From: Hemingway, David J
>
> Profiling negatives is as much art as science. There is no such
> thing as an
> ICC profile for negative because of there variability . Several years ago
> Polaroid's Image Science Lab several years ago developed some proprietary
> technology to profile negatives but it is by no means an exact science.
> These profiles were incorporated into PolaColor Insight and when
> they worked
> they worked very well and when they did not they were unusable.
> I have always recommended customers use the negative profiles as
> a starting
> point. If they work fine if not scroll through the others until
> you find the
> best starting point. With Negafix you can modify a base profile
> to suit your
> exact situation. Insight does not allow you that feature.
> The bottom line is negatives are VERY variable plus processing variations
> make them in a entirely different world than E6.

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