Google is testing in image search an interface for the preview image screen that fills in image previews into the next and previous buttons. This interface is not live for most of you but Shameem Adhikarath shared a screen shot of it on Twitter.
Here is that screen shot (click to enlarge):
Again, Google Image Search actually is constantly testing things but also, what makes it harder, is that different countries and regions show different interfaces for Google Images for local regional laws.
Forum discussion at Twitter.