How about we say "The URL you just copied links to a new image" and we don't need to show the image.

I don't think we can take it for granted that people know a PNG file is an image so I want to let them know what they're doing as they go. But I agree, it's fun to keep the surprise.

As for "new" - I think that's good shorthand to let people know that they're copying an image that isn't already on the site. I know new/old isn't quite accurate, but it's going to get wordy if we try and be technical. I like new and "current" instead of old.