To attach myself to this cause here:
I would like to propose these basic filters:
Good thing: FFmpeg already features lots of useful filters: https://ffmpeg.org/ffmpeg-filters.html#toc-Video-Filters
I agree to ffmpeg having some useful filters. One could probably modify the ffmpeg script by hand. But this is a 200€ app. Should really have a gui for such things on board. Please consider this feature request.