El 18/03/23 a las 16:43, Gottfried escribió:
> I prefer a graphical programme,
> at the moment it is easier for me.

Gottfried, I think the program called photoflare might be close to what 
you want. Try the following:

 1. guix install photoflare
 2. Start the program
 3. In the main menu, go to Tools → Automate/Batch...

You will see a new window opens where you can select all the files you 
want to transform, the transformations you'd like to apply, the folder 
where you want to save the results, and so on.

Using the GIMP graphically for the same purpose seems to require a 
plugin that is not in Guix 
(https://github.com/alessandrofrancesconi/gimp-plugin-bimp/).

Hope that helps.