I've created a small time-lapse animation film using
ffmpeg. The film would look way better if I could run a GIMP effect on all images - say, the cubism effect.
Is there a convenient way to do this?
GIMP has a Batch Mode which can probably do exactly what you need. Here is an example:
The above command performs an unsharp effect on all of the images ending with ".png".
Now we only need to find the batch command for your cubism effect.
You can also attempt using Phatch (Photo Batch Processor: http://photobatch.stani.be/).