A background-blurring portrait mode arrived last year in Google's Pixel 2 smartphone, but researchers used a hacked-together clump of five phones to improve how the feature worked in this year's Pixel 3.
The portrait mode simulates the shallow depth of field of higher-end cameras and lenses that concentrate your attention on the subject while turning the background into an undistracting blur. It's tricky to do that simulation well, though, and mistakes can stick out. For the Pixel 3, Google used artificial intelligence technology to fix the glitches.
To get it to work, though, Google needed some photos to train its AI. Enter the quintet of phones sandwiched together to all take the same photo from slightly different perspectives. Those slight differences in perspective let computers judge how far away each part of a scene is from the cameras and generate a "depth map" used to figure out the background material to blurred.
"We built our own custom 'Frankenphone' rig that contains five Pixel 3 phones, along with a Wi-Fi-based solution that allowed us to simultaneously capture pictures from all of the phones," researcher Rahul Garg and programmer Neal Wadhwa said in a Google blog post Thursday.
The technique shows how profoundly new image-processing software and hardware are changing photography. Smartphones have small image sensors that can't compete with traditional cameras for image quality, but Google is ahead of the pack with computational photography methods that can do things like blur backgrounds, increase resolution, tweak exposure, improve shadow details and shoot photos in the dark.