The Google Pixel 2 has one of the best cameras you can get in a smartphone right now. But generally speaking, these "best camera" sort of ratings only apply to the stock camera app. Google is changing that thanks to the "Pixel Visual Core"---a custom image processing chip. But what does this chip do?
First, Let's Talk About HDR
To fully understand why the Visual Core is important, you need to understand a bit about High Dynamic Range photography (HDR for short). Basically, HDR helps balance the lighting of a photograph and make it appear more natural---darks aren't too dark, and lights aren't too light.
This is mostly a problem in a couple of situations: when the background is bright and the foreground is dark---like a family photo with bright sunshine---or in situations with low light. HDR (or as Google brands it on the phone, "HDR+") has been available on Google phones as far back as the Nexus 5 to help combat this, so it's been a part of the Google Camera for a while now.
This is important to note, because while HDR isn't a new feature to the Pixel 2, its availability is no longer limited to the built-in camera app. That's the whole reason the Visual Core exists: to allow third-party app developers easily tap into the power of HDR in their applications simply by using the Android Camera API.
Okay, So What Is the Visual Core?
In short, the Visual Core is a custom-designed processor found exclusively in both the Pixel 2 and the Pixel 2 XL. It was designed by Google in collaboration with Intel, with the goal of handling the image processing work in the phones for camera applications other than the default.
To put that in even simpler terms, it allows third-party apps---like Instagram and Facebook---to take advantage of the same HDR feature that has been available in the built-in Google Camera app for a few years. Assuming an app developer uses the Android Camera API, those third party apps can now get the same quality pictures as the stock app. It's awesome.
The reason this is important to note now is because the Pixel Visual Core was disabled with the launch of the Pixel 2---Google just enabled in the Android 8.1 update, which is currently rolling out to Pixel 2 devices. If you don't have it on your device, don't worry---you will. Alternatively, you can flash it yourself using either the factory images or ADB sideload.
The Pixel Visual Core also increases the speed of HDR processing significantly---up to five times faster than using the imaging processing on the Pixel 2's Snapdragon 835 processor. At the same time, it's also more efficient, using only one-tenth the normal energy of the standard image processor. So not only does it expand functionality, it does so more efficiently and quickly.
And it even goes beyond that---or at least it will. While currently limited to third-party camera apps, the Visual Core is a programmable chip, so there really isn't anything holding it back from being used for other tasks. That, of course, is by design. Google wanted this chip to be future-proof so it can grow with the Android ecosystem. Not just for Google, but for Android developers in general. In fact, Google says it's already working on the "next set of applications" that will use the Visual Core.
For now, though, this is a step in the right direction. Opening up HDR for third-party apps on the Pixel's already-great camera is a win all around. If you're looking for some good examples of the Visual Core at work, Google has some excellent ones in this blog post.