The Third Edition of Portable Network Graphics (PNG) today became a W3C Standard.

It adds support for High Dynamic Range (HDR), and adds Animated PNG to the official standard.

https://www.w3.org/TR/png-3/

Portable Network Graphics (PNG) Specification (Third Edition)

This document describes PNG (Portable Network Graphics), an extensible file format for the lossless, portable, well-compressed storage of static and animated raster images. PNG provides a patent-free replacement for GIF and can also replace many common uses of TIFF. Indexed-color, greyscale, and truecolor images are supported, plus an optional alpha channel. Sample depths range from 1 to 16 bits.

The W3C PNG Working Group has documented the (very good) level of implementation of the Third Edition

https://w3c.github.io/png/Implementation_Report_3e/