BishopV is looking for a feature to add a watermark with the username of the viewer to images on their Discourse site. This is to prevent users from sharing images outside of the community. merefield is interested in taking on the task but has concerns about the practicality of the requirement, as it would involve generating a large number of watermarked images.
Falco points out that this could be prohibitively costly, and merefield agrees. BishopV explains that the goal is to deter users from sharing images by making it clear who shared them.
Merefield suggests that watermarking on the server or using JavaScript could be options, but both have significant drawbacks. pfaffman suggests using a site setting to prevent anonymous users from downloading attachments, but notes that this is not foolproof.
Mevo proposes adding a generic watermark with the forum name instead, which could be a more effective and simpler solution. BishopV also asks if it’s possible to track who downloads images, but Mevo and pfaffman indicate that this is unlikely.
Ultimately, BishopV seems to accept that adding a generic watermark or using the site setting to prevent anonymous downloads may be the best solution. pfaffman provides instructions on how to find the site setting, but notes that it won’t achieve the desired outcome.
im looking a customize job to create a watermark feature on images , but the watermark name base on every different member , let’s say im a user and ID name is ABC…so every images i saw with ABC watermark , if some member ID is XYZ , and those images seeing from XYZ watermark is XYZ .
not really rushing for this feature , but we confirmed really need it .
please let me know how much u can offer .
I’m a little busy right now, but would be interested to pick this up when things quieten down so your priority level might suit us both.
It could sit nicely in Topic List Previews as an option, given that plugin is used by so many image focussed sites.
I will explore feasibility for integration into the Discourse codebase and prepare an estimate for you when I get chance.
thanks robert ..hope will hear u soon .
Me too wanna this plugin
maybe we can share the cost
Isn’t this phrobitively costly?
For a forum with 10k users and 100k images you need to generate 1000000000 images for each resolution and thumbnails.
I’d interpreted the requirement differently, but could be wrong! 
@BishopV are you suggesting that when a user uploads an image, a watermark is added to the uploaded image to reflect the username who uploaded them?
Robert , nope I mean every viewer have different watermark based on viewer username. Not the uploader .i think @Falco he right
In that case I share his concern at the practicality of this requirement. What is your business case for this feature?
Just we don’t want people share our picture to others and at least we know who’s are shared . And if the feature there he might be not dare to share
Got you.
There’s no way you could practically pre-process for that.
You either have to watermark on the server, when serving the images (blimey, hope you’ve got deep pockets for an almighty computer, even if that were possible).
OR
One could try and watermark on the javascript layer … I’m not sure how easily that would integrate … can’t image the performance of that would be good … and it would be insecure and open to hacks (because you’d have had to serve up the originals)
Perhaps someone here has experience of doing exactly this?
The best you can do is this site setting:
Mostly, if you put something on the internet, then people can get it.
Wouldn’t it be far easier to add a “generic” watermark with the forum name ?
As you say, @BishopV, usually a watermark prevents people from sharing the image (at least publicly), and in any case, prevents them from claiming ownership/being the author.
I guess that anybody a little clever and wanting to get images to spread them, would create another user just for that purpose. So, you are willing to go a pretty complicated route for probably no good reason. A generic watermark seems a good solution to me.
Btw any possible we can know who’s download the picture ? Or specific which images ?
If I understood correctly, his problem is specifically with images, so I guess this wouldn’t help, or would it ?
I’m not 100% sure, but I don’t think so. If the image is loaded to be shown in the user’s browser, then it probably can be saved without you knowing it.
I think this is the best and last solution I can do . Btw how to prevent people download it ?
You would turn on the site setting that I called by name. Do you have discourse installed?
Hi jay , yup we are using discourse right now , just not sure where is the setting .
This does not change any behaviour with respect to images, only for non-image attachments.
Oops. Thanks, Richard. I didn’t post close enough attention. I was thinking that it would break images for all non logged in users, which didn’t quite make sense.
To find it (though it won’t do what you want) you would go to system settings and search for ‘prevent’. The search here is really powerful, searching the setting titles, descriptions, and values.