It seems that Google is rolling out a new design for the previews within image search results. When clicking on an image, rather than loading the preview in a black background frame, Google now displays the image preview on the right-hand side. There are several folks who are seeing this design and interface. When testing it out for myself, I was unable to replicate this.
The following image is from Barry Schwartz:
Is this rolling out for everyone? At this point, we’re going to assume this is a limited test.
It seems that the purpose behind the new design is to make the preview window less noticeable. If less people saw the preview window, it could lead to fewer clicks on the image that take the search to the page with the image on it. In the end, it would lead to less traffic to the site hosting that image.