Lead Developer
The trouble with this is you would need to insert the category name into the container with the image itself.
In order to do that, you would need to overwrite the post image function, or I would need to add a hook into the image container (might be a good idea anyways).
I know this type of thing is possible with my WP Show Posts plugin: https://wordpress.org/support/topic/placing-post_tag-on-the-top-of-image/
I’ll look into adding a hook inside the post image container as well in GP.