Hello and congratulations for you great work.
I just tried imgen with k2 and i had several problems. For example i setted to resize the folder images/stories content and chose only article view and worked fine with the watermark but some other images that i was using on my sites footer got disappeared and it's weird because those images are on a different folder than images/stories. Is this powerfull tool compatible with K2 have you tried it?

Thank you very much

If you are using the Custom HTML module for your footer you may find that setting the 'prepare content' parameter in that module to 'no'. If it is set to yes then the module will fire content plugins, it sounds as if the plugin is being applied to your footer as well, which you don't want.