Note: The plugins work for Gimp2. They do not work for
Gimp3 unless somebody ports them to Gimp3.
Gimp plugins to modify a path, currently four. To get
the plugins, do:
At the bottom of this page there are Download buttons. Clicking one
you get a .ZIP file. Unzip it and put the python file it contains in
your Gimp's plug-ins folder and restart Gimp.
This registers in your Gimp the chosen plugin(s), one of:
Simplify
Round path corners
Simple smooth
G2-continuity
Join strokes
To find the plugin(s) in Gimp, go to the Paths tab and right-click
the path you are going to modify. This opens a pop-up window. At the
bottom follow the link Tools > Modify path > ...
and choose.
No instructions are given here. Just experimenting should suffice. Some
explanations and pictures appear at the sites on the right.
Behind the plugin G2-continuity there is quite a bit of mathematical
theory, developed by myself based on earlier work by Stuart Kent. It can
be found in the thread mentioned above, but since it may be useful more
widely, I include here the version from march 2022 (which will very
probably be the final one):