Re: [Gimp-user] Scanned negatives, moire patterns and GIMP?

[Pat David <patdavid gmail com>]

These are usually referred to as "Newtons Rings", and are from contact with
the negative backing side being placed against the scanning glass.  Liam is
right that there are better negative holders to keep the physical negative
away from the scanning glass to stop this from happening.  A short term
solution could also be to scan the negative with the emulsion side down
(but be really, really careful you don't scratch it).

http://en.wikipedia.org/wiki/Newton's_rings

Unfortunately, a fourier transform won't solve the problem, as the pattern
is circular in nature, and localized at the contact points (so a different
problem than the neat solution provided by Thorstein's video).

On Sat, Dec 6, 2014 at 5:29 AM, Thorsten Stettin <thorsten stettin gmail com
> wrote:
>
> Am 05.12.2014 um 21:34 schrieb Keith Purtell:
> > Here's a link to one portion of the image:
> >
> > http://i.imgur.com/6RaV68i.jpg
> Try this via G'MIC: https://www.youtube.com/watch?v=3137dDa6P4s
>
> I hope this helps. :-)
> > On 12/4/2014 7:11 PM, Liam R E Quin wrote:
> > > >   If they can't resolve this, what are my chances of solving the
> > > > problem
> > > > with GIMP? I tried a few of the existing filters without visible
> > > > results.
> > > > My first Google searches haven't turned up a good detailed tutorial on
> > > > moire removal.
> > >
> > > There's a G'MIC filter for it. But it depends on the exact nature of
> > > the pattern as to what's best. I get them when scanning colour books,
> > > because of the way the books are printed (it's actually unavoidable
> > > unless you use a "descreen filter" in the scanner driver, but better
> > > to do it in GIMP). For that, separating into layers and using
> > > gaussian blur is often best, but another possibility is to use
> > > wavelet decomposition and delete that high frequency layers. G'MIC
> > > has a filter to do that, too.
> > >
> > > If you can share a sample I can have a better look.
> >
> >
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>
> --
> Lao-Tse sagt: Nichtstun ist besser, als mit viel Mühe nichts zu schaffen.
> Und er sagt auch: Ich habe drei Schätze, die ich hüte und hege.
> Der eine ist die Liebe, der zweite ist die Genügsamkeit, der dritte ist
> die Demut.
> Nur der Liebende ist mutig, nur der Genügsame ist großzügig, nur der
> Demütige ist fähig zu herrschen.
>
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-- 
pat david
http://blog.patdavid.net