The last Google Image update seemed to be an image filter update in September. But now, the update seems a bit more outside of the scope of what we would classify as a filter.
WebmasterWorld administrator, tedster, observed:
I started seeing some really wrong captions on some images, where the algo is pulling the caption from on-page anchor text. How can on-page anchor text be a candidate for naming for an image that is also on the page?
Senior member, zeus, who reported the image update has seen tons of images drop out of Google Image search, plus he has seen a possible hotlink image bug. The hotlink image bug happens when a third-party site links to a specific image and Google classifies that image from a a third-party domain.
Forum discussion at WebmasterWorld .