We analyzed the image search traffic of 87 domains and found a 63% decrease in image search referrals after Google’s new image search UI was released. Publishers that had previously benefitted the most from their image optimization efforts suffered the greatest losses after the image search update, experiencing declines nearing 80%.
In the eleven weeks after Google’s new image search was released, there has been no recovery – which means for image search, the significantly reduced traffic levels we’re seeing is the new normal. In the aftermath of the new image search experience, image SEO has been severely compromised, and we have no choice but to recommend deprioritizing image SEO when weighed against other search traffic initiatives.
How can I see image search traffic in Google Analytics?
Here's one thing you can do: In new-style image search, an image file is requested when the user clicks on an image in search results. The referer at this point is "blank.html". (Literal text "blank", not a blank referer.) Rewrite image requests with this referer to a single-pixel gif set to expire immediately. This has no effect on the user, because they don't see the image yet; it's been requested ahead of time to make the search look more efficient. If the user clicks again, their browser has to make a second request-- and this time there's a different referer, so your rewrite doesn't kick in and they see the image.
Now you've got two data points: The preliminary click in image search, and the follow-up click, separately logged. Even if you don't end up learning anything useful, you've saved yourself some bandwidth.