If your images are on AMP pages, Google will now show the AMP URL, along with the icon, in the mobile image search results.

Here is what it looks like:

When viewing images in image search, you can’t actually tell whether the image is on an AMP page until you select and image and Google expands it to show the additional information about the image.  Google will show the lightning bolt icon with “AMP” before the site title.

When you then click through to the page, it will come up with the AMP version of the page where the image resides.

There is an interesting thing about this.  When the images are shown in the regular search results, Google does not default to the AMP image page.  Instead, it goes to the regular non-AMP image.  But when viewing it from image search, it will then show the same identical logo from the same site, but defaults to the AMP one.

Here is the logo in the regular search results, and then expanded.

Then clicking more images brings up the same initial four images, and now it is the AMP version.

It isn’t clear why Google would have made this choice though, especially showing it in two different page formats for the identical image.