[FFmpeg-user] lenscorrection and vignette filters

[Michael Koch]

> I can't help you much, but you are free to look at the source code, and
> see whether you can see the formula from it:
>
> https://github.com/FFmpeg/FFmpeg/blob/master/libavfilter/vf_lenscorrection.c

I did already try that, but there are no comments in the source code, 
and it's really difficult to understand how it works. Reverse 
engineering from the results seems easier for me.

Michael