[filmscanners] Black levels mangled in Nikon Scan (?)

["Julian Vrieslander" <julianv@mindspring.com>]

I'm appending below some excerpts from a current thread in the usenet group
comp.periphs.scanners.  This information (if true) seems to confirm what
some of us have been suspecting - that NikonScan messes with black levels in
a peculiar way.  The symptoms show up as a loss of shadow detail, or as
discontinuous shapes and sharp cutoffs in histograms.

I've wondered if this was a bug, since VueScan produces smooth histos from
the same slides.  But now we learn that this might be a "feature"
intentionally provided for us by Nikon, so that more of our scans will come
out contrasty, and with the same dark blacks and blocked up shadows that we
are used to seeing in drug store prints.

Perhaps someone on this list can provide a more technical explanation of
what it going on here.

*****

From: "Bruce Feist" <bfeist@flock.org>
Newsgroups: comp.periphs.scanners
Subject: Levels in LS-4000 with NikonScan

I've noticed that whenever I scan a color negative with my LS-4000 and look
at the levels, there's nothing at the far left.  That means that there's
nothing purely black, right?  The curve becomes non-zero at the same point
in each negative, so I've created a user setting which sets the black point
to where that happens.  Is this a logical thing to do? Do other LS-4000
users see the same thing?  Should I be worried about it?

*****

From: "Bruce Feist" <bfeist@flock.org>

I asked Level 2 Nikon support about it this morning, to see if they were
aware of the problem and hopefully working on a firmware upgrade to fix it.
The technician was very knowlegable; he knew that it didn't show up in the
older scanners -- and he says that it was done deliberately; it's not a
problem with the scanners.  With color neg film in particular, people were
complaining that even totally unexposed film wasn't producing true blacks,
so their blacks weren't black enough... so Nikon padded things out a bit to
create the possibility of truer blacks.  Blacks aren't being clipped out;
the colors are slightly compressed to make room for them.

One way of using this is to create custom settings for different films you
use frequently which put the black point at the appropriate place for that
film.

If what I'm saying doesn't make sense, please blame it on me and not the
Nikon guy; I could have confused something or other, but I'm confident at
this point that the levels aren't a bug.  (It's conceivable that they're a
judgement error on Nikon's part; I don't know enough to judge that.)

*****

From: East75th <east75th@wo.EDITOUT.rldnet.att.net>

Bruce:

If you look at the histograms, you'll see that in the adjusted image's
shadow area detail  has been trashed because the information in that area
has been compressed-out by Nikon's "feature."  There are ways to adjust the
shadow area blacks without having the manufacturer's software presuming
what's best for you, and that's assuming one is satisfied with the results
that NS 3.x produces. Given the response I've seen elsewhere and gotten by
e-mail, a lot a people agree with me that the result of  NS 3.x negative
scans range from strange to ghastly.

Because there's a workaround available, it's not such a big deal to people
who know how to use scanners.  However, it should be a trivial matter for
them to alter NS to make the use of that feature an option so that everyone
is happy.

Regards,
Dane

--
Julian Vrieslander <julianv@mindspring.com>

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