What are HDR, Auto HDR & Smart HDR shooting modes and how do they boost my iPhone photography game?

Smart HDR is like regular HDR, only smarter. Smart HDR first appeared on 2018's iPhone XS, iPhone XS Max and iPhone XR. It takes full advantage of the advanced camera sensors, the power of the A12 Bionic chip's Neural engine, machine learning, artificial intelligence, computer vision and the latest computational photography advancements. With Smart HDR, all iPhone photographers can effortlessly take beautifully-lit photos with great dynamic range.

tvOS 11.2 release notes

Released on December 4, 2017, the tvOS 11.2 software update brought a pair of new HDR viewing options for Apple TV 4K owners along with access to a brand new Sports tab within Apple's TV app and assorted under-the-hood changes and fixes.