Hi guys and Zeus,
1. I couldn't see major changes in german Google image search. (Only some small changes that seems as Googles works on the "duplicate Images" Problem (t.m. same picture in the image-serps twice or more). Btw: We have in Germany a "image-search-index" called "bidox" - it confirms: no big changes at all...
2. All my english-galleries have the same traffic since months. From my point of view I can't confirm a major-update in the englisch image-search.
3. In my observations the last "big Update in image-search" was "freshness" (some months ago).
4. All you described sounds to me like a "safesearch-filter-problem". Did you checked your domain with the site-command (site:yourdomain.tld in the Google image-search)?
5. 'm sure the Panda, Penguin or other Web-Spam-Updates doesn't effect the images-result. A "web-spam-filter for images" - especcially for hotlink-farms - is missing!
6. Conclusion: I wait for a major image-search-update - guess we all do :-)
Best wishes, Martin