[ptx] Vignetting correction in nona

[Mike Runge]

Sounds to good to be true :-)
Pablo,
#1 will there be some kind of preview? I would like to see this as 
option in the regular viewer.
#2 will this feature be supported by the lens settings import/export?

best, mike
 
pablo.dangelo at informatik.uni-ulm.de wrote:

>Hi all,
>
>I'm currently implementing a vignetting correction during remapping. The
>following things will be implemented:
>
>Gamma correction prior to the remapping. This is similar to the gamma value
>supported by PTStitcher.
>
>Two vignetting correction modes:
> 1. correction by addition: i_new(x,y) = i(x,y) + corr(x,y)
> 2. correction by division: i_new(x,y) = i(x,y) / corr(x,y)
>
> The first case is similar to the vignetting correction implemented in panotools
> plugin and suitable for gamma corrected images (like the typical gamma 2.2
> (or something similar) of the images output by scanners or a digicam.)
>
> The correction by division should work best with linear images (gray/color
> values proportional to light captured by the sensor)
>
>The correction offset/factor can be specified by a polynomial which depends on
>the normalized distance r (0..1) between point (x,y) and the image center.
>
>corr(x,y) = j + k*r^2 + l*r^4 + o*r^6
>
> where j, k, l and o are variables specified in the stitcher script file.
>
>or a flatfield image (flat):
> 1. for additive correction
>     corr(x,y) = flat(x,y)
> 2. for correction by division:
>     corr(x,y) = flat(x,y) / max(flat)
>
>I decided to use different interpretations of the flatfield image because it
>should then be possible to just feed a captured flatfield image into nona.
>
>Any further wishes or thoughts?
>
>ciao
>  Pablo
>
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