[Digikam-devel] Patch: fix automatic correction of lens chromatic aberration

[Andi Clemens]

Ok so I'll wait for another update...

Andi

On Tuesday 10 March 2009 08:56:48 Matthias Welwarsky wrote:
> On Monday 09 March 2009 11:30:27 Andi Clemens wrote:
> > I will take a look it the patch now...
>
> I've taken another look into it, seems its not complete yet. Geometry and
> distortion correction also need subpixel access, and I've found that it
> doesn't work any more if I check "16 bits color depth" in the "Raw
> Conversion" settings.
>
> > Andi
> >
> > On Sunday 08 March 2009 19:51:12 Gilles Caulier wrote:
> > > Matthias,
> > >
> > > Thanks a lots. this patch solve a task from my TODO list.
> > >
> > > This patch is a good candidate to go to 0.11 development branch and, if
> > > it doesn't break i18n, in 0.10 (trunk) before finale release.
> > >
> > > Marcel, Andi, can you check this patch for me and guide Matthias on the
> > > right way. I'm very busy here to prepare my evening classes
> > > presentation for next Wednesday. To test, just use these pictures :
> > >
> > > http://digikam3rdparty.free.fr/TEST_IMAGES/LENSFUN/
> > >
> > > Thanks in advance.
> > >
> > > Gilles Caulier
> > >
> > > 2009/3/8 Matthias Welwarsky <matze at welwarsky.de>
> > >
> > > > Hello,
> > > >
> > > > the attached patch fixes CA correction in the lens auto-correction
> > > > tool. The fix
> > > > consists of two parts:
> > > > 1.) set Alpha component of corrected pixel to "fully opaque",
> > > > otherwise corrected image is not visible (trivial)
> > > > 2.) Implement sub-pixel interpolation in class DImg, necessary for CA
> > > > and CI
> > > > correction with lensfun.
> > > > There are two new pixel color accessor functions: getSubPixelColor()
> > > > and getSubPixelColorFast(). The first one uses Lanczos interpolation
> > > > to compute subpixel colors, the second one bilinear interpolation.
> > > > Lanczos yields better
> > > > results, but is a lot slower than bilinear. Before using
> > > > getSubPixelColor(),
> > > > prepareSubPixelAccess() needs to be called to precompute the Lanczos
> > > > kernel.
> > > >
> > > > Lanczos implementation was adapted from ufraw, Bilinear was
> > > > implemented according to Wikipedia description.
> > > >
> > > > I would be happy to hear comments on how to optimize the computation,
> > > > it's probably not optimal yet.
> > > >
> > > > regards,
> > > >         matthias
> > > >
> > > > _______________________________________________
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> > > > Digikam-devel at kde.org
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> >
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