Just click the shutter in Photobooth mode and Google's AI will begin analyzing what it "sees" -- what Google calls a "quality assessment." At the same time, you'll see a visual indicator (in the shape of a white bar) that increases in size based on the algorithm's rating of the frame. This varies depending on whether the subject or subjects have their eyes open or closed and are displaying one of the registered expressions. A high score will trigger the shutter, capturing what the AI deems your best selfie.
Photobooth is a by-product of Clips, Google's hands-free camera that automatically records short videos when it senses something interesting is going on. And seeing as Clips never really took off -- even Google has stopped selling it, reports The Verge -- Google is integrating its smarts into a product people actually bought.