Full Size picture showing up on mobile SERP

[JeffClevelandTN]

Wow! I woke up this morning to do a little work and was REALLY surprised to see that Google displayed a Full Size rectangular image instead of a small square image on mobile SERP. At first it seemed to be a bit random, but it became easier to replicate. If this feature is fully rolled out, it may create a lot of work (and opportunity) for websites that were optimizing primary images to be square to get an image on mobile results. The screenshots show the differences of SERPs with a square image versus a rectangular/landscape image and a collage of pictures.

The first screenshot shows a full size image, the 2nd screenshot shows an image that is kind of between square and rectangle and you'll notice that it doesn't benefit fully from the full width as shown in the first screenshot image. Here's where it get's really interesting, the 3rd and 4th screenshots shows several things. You see the first and third results have the "normal" thumbnail, while the middle shows a collage of images. What I've found in my very limited research:

• If the primary page's is a square image and there isn't any other images on the page, it uses the traditional thumbnail image.
• If the webpage has several images but none of them are fully rectangular (16:9 ratio), Google uses the collage.
• If the webpage has multiple images, including rectangular and square it will also use the collage
• Google will display occasionally display a collage with five images, one larger and four small.
• When the collage is used, it will have a minimum of three images, one larger and two small. (4th screenshot)

Is anybody else seeing this? I first saw this using the Google Anonymous Ad Tool (mobile device), then I immediately tried on my phone.

At least for me, it doesn't seem to matter if I'm logged into a Google account or not. However, these results ONLY show up when using Chrome browser, not Firefox. I have a Samsung phone, and being the weekend, rest of family is sleeping in late, so I had to sneak and quietly borrow my wife's iPhone. Similar searches on her iPhone (using Chrome) will very rarely show a collage, but I couldn't get a SERP with a full size single image. But I didn't get to do a whole lot of iPhone testing. Also, doesn't seem to be affected by whether the image is jpg or webp.

 

[JoyHawkins]

I've seen the carousel before. Not sure I've ever seen the full-size image but that is awesome!

 

[JeffClevelandTN]

Update: I've found that the easiest way to trigger the full size image and/or the photo collage is to do a localized search using a phrase similar to this: "best industry near me" or "best industry cityname". For example: "best mexican food near me", will show full size images, BUT.... "mexican food near me" does not.

I was able to replicate this on Google's Anonymous Ad Tool, here are example links that maybe will trigger it for other people too:
best mexican food atlanta ga
mexican food atlanta ga (no full image)
best whitewater rafting knoxville
whitewater rafting knoxville (no full image)

Google seems very picky about the industry and the use of "best" in the search phrase in triggering a full sized image. Also, now the max images I'm seeing in the photo collage, is three versus five, for the same searches done yesterday.