The next version of Windows 10, now known as 1903 or 19H1, will support AVIF format. It is a modern image format based on AV1 video format, developed by Alliance for Open Media.
AV1 is the latest and largest of the open video formats. It is designed as the successor to VP9, which competes directly with the proprietary (and expensive) codec HEVC / H.265. It is intended to be combined with the Opus audio codec to create WebM files for web video HTML5.
AV1 today is supported by many industry giants (Amazon, AMD, Apple, Arm, Cisco, Facebook, Google, IBM, Intel, Microsoft, Mozilla, Netflix, Nvidia, etc.).
The AVIF image format formats an AV1-based image format. It is already supported by a variety of software, including VLC and Firefox. And from Windows 10 19H1 and on, the AV1 format will be supported from at least File Explorer and Microsoft Paint.
So if you have Windows 10 Build 18305, you can try this new feature in action to see if you can display AVIF images with the paint image editor, of course after installing the AV1 Video extension.