Okay, looking at numbers. My site enjoyed a 70% drop today. Sound bad? So today was a flashback to about 3 years ago. For 3 years this site has kept a very respectable and steady traffic. It didn't really waiver, never caused concern. I stopped working on this site months ago for fear of waking up to a flat line. I spent time at the Adsense in your City team going over this site a month ago. I decided recently to work on this site again. You could say I lost that "fear" of disappointment and felt secure enough that I wouldn't be wasting my time on it. Well, we're here today and guess what? With a 70% drop I can say you got me this time. Funny how the world works. This is getting to be an ugly business. I have a thick skin but this one? Not sure how to react other than wait. For me, and my decision to not work on it, then work on it and then see this? It's a major slap in the face.
Aside from that, I see another one of my sites with images ranking well with marginal change. Another site which is more product related? It appears you need to have your own camera photographed images at this point. Mission accomplished, less duplicates.
Quite a lot to digest here. I sense for the most part image search may get a collective "shrug" around here. Guess we will find out. Frankly I can't find any other details of this anywhere which has me wondering.