Replace existing image

Flickr offers this feature to paying customers. But I think it can cause more trouble. A prankster can host a regular image and share it through Reddit and other social networks. If the image becomes popular, he can easily swap it for a nasty one. Imgur is not like Flickr. It remains a public image sharing service even though you can store images privately. Images are not shown with their owner's name so it is hard to see if a shared IMGUR image is for someone's own private use only.

Good point. I never thought of it.

Thanks, Sushubh! That's exactly the reason, and I couldn't have said it better myself.

Too bad I did not know this a week ago when I uploaded placeholder images to generate links for use as QR codes. Now I am screwed, because the QR codes are already in place.

It is always a good idea to have links to your own domain which are totally under your control for campaigns. That ways, you have the ability to change the final link by editing the redirection on the links on your own domain.