Here is the thing.
I created a gallery and different users so specific people can view the images. No one can register.
I would like to add a watermark on the images depending on the user visiting the website. If an image is shown somewhere else on the web, I could know which user leaked it looking at the watermark on it. Each user would have his own watermark which would be added on the image dynamically when he visits.
I have a login page with the user name and password. I guess I have to add in the php file of the watermark plugin something like
if user=user1 then put watermark=user1 on image etc. I don t know how to code php so this is of course not proper code but just the idea.
Thank you !