The Pixel Visual Core is a custom image processing unit built into the Pixel 2 and its bigger brother the Pixel 2 XL. It sits alongside the DSP built into Qualcomm’s processor, allegedly allowing for much better photos to be taken. After all, proprietary hardware and software usually mesh well.
They still use Hexagon (QDSP) from the Google Camera app on the Pixel 2 (XL) just like the Pixel (XL) and they still have a special google_camera_app SELinux policy domain. Other apps can’t do what Google Camera does right now.
— CopperheadOS (@CopperheadOS) February 7, 2018
However, it looks like the stock camera app on the Pixel 2 doesn’t actually take advantage of the Pixel Visual Core, instead opting for proprietary software processing on the Qualcomm Hexagon DSP to get the amazing results we see with the Google Camera app. Brian Rakowski, vice president of product management at Google addressed this issue over at FoneArena:
“Turns out we do pretty sophisticated processing, optimising and tuning in the camera app itself to get the maximum performance possible. We do ZSL and fast buffering to get fast HDR capture. So we don’t take advantage of the Pixel Visual Core, we don’t need to take advantage of it.”
The Pixel Visual Core is for third party apps, giving other app makers the advantages of Google’s advanced photo capabilities via an API and specialized processor hardware. It’s strange that Google’s own camera app does not use it, but it makes perfect sense why it’s in the phone.