I have several hundred files all of which I need to do the same thing to.
How do I do that (other than hanging myself after trying to do it manually)?

Any help! Seriously needed to get my feet wet One can't swim without someone teaching you how to get in the water

Remember Gimp is a very comprehensive application with a steep learning curve.

There is a batch plugin BIMP that you might use (depending on OS) see:
http://www.alessandrofrancesconi.it/projects/bimp/

If using gmic, I advise using the older version 1.8 I think there is a problem entering parameters with gmic2, edit: I use linux, had the executable write permissions unset - so gmic2 does work, however FWIW you run a test image to get the required parameters. Gmic will write to a logfile if required.

Maybe something like this: http://i.imgur.com/YIaguAD.jpg The same applies to any other filter/script/plugin you want to use.

Once you have all the parameters, add them to BIMP as actions. Two for example, gmic followed by the gimp impressionist filter.
screenshot: http://i.imgur.com/K7ajmCt.jpg

Just one image as an example, but you can add a whole folder full. Opened up in gimp the result: http://i.imgur.com/kI5MrQa.jpg

GMIC can run as a command line application, much better for batch processing than going through Gimp.

Hello, perhaps the following might be helpful as well:
https://paulsphotopalace.wordpress.com/ ... s-at-once/
At the bottom of that article there's a link to a second article, explaining how to apply several g'mic commands to a series of photos.

Where to find out how to set parameters, i.e. gimp commands in bimp as actions, is there some add action button as well? Where would i get a list of the gimp scripts' keyword syntax that would be recognized in bimp, in the gimp scripts did I presume, I hope I am right?

If you looked at the BIMP webpage there are examples there, but apart from built in dialogs - resize - crop - watermark etc there is a 'other gimp procedure' option. The big square with a plus adds incremental actions.

Use the filter in Gimp to determine the values to enter in the BIMP dialog. example: http://i.imgur.com/ZRG1JIF.jpg

G'mic is a little different, there are only two parameters input layers, set that to 1 and a command string. If you are clever you will have determined this without any help and can skip BIMP and use gmic in a batch file as mentioned by ofnuts. I have to use the option to write to a log file see: http://i.imgur.com/YIaguAD.jpg which might look like this


and from that extract

to copy and paste into BIMP.

You can of course save the total set of actions in a bimp file for later/repeated use if you want, a matter of using BIMP to see what it does and does not do. Generally most of the Gimp filters work, but not all. Some but not all third party scripts will also show up. Use the BIMP search function and a keyword (a sensible guess)

edit: It might help if you gave your OS & version.