Well, it might drop even more now. Google has quietly added a new feature named "try these too." When you click on an image and Google shows you a larger preview of the image, Google is actively showing you other images you might want to look at as well.
You can see this in the image above, listed on the right side of the image, under the "view page," "view original image," and "image details" buttons.
Are you happy about this? It seems like many are not.
Forum discussion at WebmasterWorld.