Starting yesterday I started noticing many many complaints in the Google Web Search Help Forums about Google Image Search. In short, some users were unable to trigger the preview to show a larger image, even after clicking on the image. Google is aware of the issue and is working on a fix.
Andy B. from Google wrote:
Thanks all for sharing details of the issue you’re experiencing enlarging images. The relevant teams are aware and investigating, and we’ll be posting updates to this thread as they become available.
To clarify, this is a separate issue from the one originally reported on this thread (although the end result is similar).
There seems to be complaints from all types of users, using all types of browsers.