color correction & vignetting [Re: [ptx] Hugin wishlist, RFC]

[Kai-Uwe Behrmann]

Hi,
I underway to code an analysing of overlapping areas in an remapped pano.
Therefore it is difficult to reproject to the older original images in
order to do an proper devignetting.

So I think I can do something for:
- different exposures for partitial images and
- with areas of different side dispersion
These two stages (devignetting/blending) my be later combined.

The band blending differs from my approach, as it is radialy
searching for colour differences in the origin images, as I understood
the paper correctly. This, band blending is able to do devignetting at the
same time.
The capability to do an transformation from origin image to pano
positions and back could help doing good corrections.

At the moment I have not the time to continue. If an other urgent project
of mine gets soon finished I hope to contiue this month. Anyway if someone
start to work on blending, please let us know.

best
Kai-Uwe

Am 04.02.04, 09:30 +0100 schrieb Pablo d'Angelo:

> On Wed, 04 Feb 2004, Pablo d'Angelo wrote:
>
> > Before we start with exposure compensation we have to tackle another lens
> > defect, namely vignetting. I found that my camera produces gray level
> > differences of ~ 40, if zoomed out.
> >
> > The pano tools plugins have a simple p = b*r^2 * p  (where p=pixel value)
>
> Ehm, sorry, pano tools uses additive instead of multiplicative correction
>  a*R^2+b  (b=brighness), a=coefficent. See also:
> http://www.email-lists.org/pipermail/ptx/2003-October/000721.html
>
> I'm not sure if we should go with a formula (simple for the user), or if we
> should use a flatfield, like it's done in astronomy. Comments welcome.
>
> I think the flatfield is harder to create. on the other hand, maybe its
> feasible to fit the parameters for the correcting, radial function if images
> with high overlap and without scene changes are used.
>
> ciao
>   Pablo
> --
> http://wurm.wohnheim.uni-ulm.de/~redman/
> Please use PGP
>