[FFmpeg-devel] Vignette filter limitations...

[Evert Vorster]

Hi there, Clement.

Thanks for the reply.
Unfortunately, coding is not my strong suite, I would not even know where
to begin looking.
The "backward" switch was a big clue that this vignetting filter is more
for the effect than actually removing the vignetting effect from footage.

The lens corrections are taken care of, fortunately, by nona being able to
output an x and y pair of remap files that ffmpeg is able to use in the
remap filter.

I am aware of the lenscorrection filter, but from my reading of the manual
it deals more with lens distortions rather than chromatic aberrations.

Of course, far quicker than continually calculating the vignetting &
chromic aberrations, it would be faster to apply a color map to the images,
either before or after remapping, but I have not figured out how to do
that, either.

Currently I am exploring all the options, and hopefully I will find
something that is easy enough to use.

Kind regards.
-Evert-

On 27 August 2017 at 16:31, Clément Bœsch <u at pkh.me> wrote:

> On Sun, Aug 27, 2017 at 08:33:30AM +0100, Evert Vorster wrote:
> > Unfortunately I have a real problem with vignetting.
> > The vignette filter in ffmpeg seems to have some room for improvement.
>
> Yeah, definitely: the vignette filter was written with the fancy
> vignetting effect in mind (think of it as a filter to simulate old school
> movies to be used with an additional vf curves=preset=vintage). Making a
> backward mode was made because it was relatively trivial to make, but it
> certainly is currently pretty limited for actual corrections. Patches
> welcome. The code is not very complex, and if you can understand the
> underlying maths (which you probably do given the project you're working
> on), adding options to the filters for your needs should be accessible.
>
> Also note the existence of lenscorrection filter, which may, or may not be
> of use while trying to improve the vignette filter.
>
> [...]
>
> Regards,
>
> --
> Clément B.
>
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>
>


-- 
Evert Vorster
Isometrix Acquistion Superchief