I posted about this same filter a few weeks back. Maybe you can get some tips from that thread:
It is a shame there’s not better documentation. These filters are really powerful. But to lean how to use them, you have to piece together a bunch of different posts to get to what you want. Gmic had a wiki page set up where they were going to have documentation on all the different filters, and I think there was one entry there out of the dozens available. I just spent 10 minutes looking, but can’t find that wiki page again. I was going to offer to start writing some documentation for them as I figured things out on my own.