Indeed, the owner is normally the uploader unless it has been changed afterwards.
There is no template function but an image class method `getOwner()`:
https://docs.zenphoto.org/source-class-Image.html#1228-1237
So in the theme's `image.php` or within the next_image loop on `album.php` you can use the global variable to get it like this: `echo $_zp_current_image->getOwner()`; This will be the user name, if you want the "nicename" if set you would additionally have to use the adminstrator class to get that from the user account: https://docs.zenphoto.org/class-Zenphoto_Administrator.html