Google Images on Top of Serps

Can you optimize for this?

[Rick42]

Google has started showing SERPs with image previews at the top of the page for one of the keywords in my industry, and I was wondering if anyone has seen this pop up recently as well for their industries.

I am curious to know what algo Google is using to choose which pictures to use. From my analysis, I have observed that there is no particular denominator...but Google seems to simply post random pictures.

Anyone care to share their thoughts on this?

[hawleyca77]

Part of the algo appears to be using image labeler:
[images.google.com...]

I've also seen some relationship with the keyword and pixel size, as far as what gets ranked higher.