* Photographer published a photo on their own website
* Tweeter posted it on Twitter, the credit line is preserved.
* Retweeter retweeted it. The photo thumbnail in the reweets are trimmed in the timeline. Tapping on the photo to view it in full, you can see the credit line.
* Photographer sued Retweeter for distributing their work without proper credit.
I'd be pretty pissed if my chance at exposure was blown because the one time it got spread virally it got spread without visible attribution. With visual attribution 10s of thousands or even millions of people see my name. Without visible attribution (having to click through to a larger version) I've effectively been robbed of $$$$$$ PR
I work on lots of open source and of course all my attribution requirements (BSD, MIT) don't require things to be upfront but I posted a photo online with my name in the corner and someone cropped it out I'd be pretty pissed.
I suspect for photos it's even worse. I have 7k photos CC-BY on Flickr. If people post them to twitter I doubt they add the required attribution. Maybe CC should start requiring or at least recommending attribution to be embedded in EXIF for images so that Twitter etc can automatic provide visible attribution AND include the same EXIF text that in any scaled versions they generate so that if someone reposts the scaled versions the attribution continues. Of course people can remove the EXIF or replace but that's not what we're talking about here. We're talking about some photographer getting unintentionally cheated out of PR.
* Photographer published a photo on their own website
* Tweeter posted it on Twitter, the credit line is preserved.
* Retweeter retweeted it. The photo thumbnail in the reweets are trimmed in the timeline. Tapping on the photo to view it in full, you can see the credit line.
* Photographer sued Retweeter for distributing their work without proper credit.