Watermark existing pictures?

[FDSFVN]

Hi, I've installed the cpg 1.4 modpack by Stramm, in the configurations it's possible to activate watermark, but how can I watermark the pictures that are uploaded before I installed that modpack? Does it give a configuration or menue or something like this to do that?

Thank you very much!

[Stramm]

Please read the modpack docs in the modpack announcement thread.