Smartphone 4K HDR in action: check out the Sony Xperia XZ Premium's display

Sony's latest high-end smartphone just made its debut at MWC 2017, and its biggest feature is a bit of a blast form the past. Sony was ahead of its time back in 2015 when it introduced the Xperia Z5 Premium, the first smartphone ever to squeeze a 4K screen's worth of pixels into a tiny, pocket-friendly form-factor. While other manufacturers have been content to top out at quad-HD ever since, Sony's stepping back up to the plate with its sophomore 4K smartphone effort, introducing the new Xperia XZ Premium.

We already got an early look at this 4K phone, but our initial ...