There were two separate attempts at creating an animated PNG format back when. “APNG” and “MNG”. I Firefox even supports APNG. I guess that was never part of the PNG spec, though. Just a separate image format that was loosely inspired by PNG and also supported animation, I guess.
MNG tried to do everything (iirc it could even embed links, did play/pause, and seeking, like a static version of Flash), not surprising it didn’t catch on. APNG was a simple enough extension that everybody just ended up using that instead (The only browser that doesn’t support it being IE and IE-era Edge). Now the W3C is handling PNG, they just accepted that reality and added it to the official spec now.
It’s good to see that lots of programs already support some or all of the changes, but I didn’t see anything in the article regarding backwards compatibility. EG if you have an animated PNG will older programs error out or just display the first frame?
APNG will display the first frame on app that doesn’t support animation.
I would need to read the full spec for be 100% sure, but the PNG format makes it easy to make backwards compatible extensions so I would be surprised if there’s anything in the new spec that isn’t.
Yeah from a quick glance over the spec it’s basically just small clarifications, promoting existing extensions (EXIF and APNG) to the core spec, and adding the new HDR metadata chunks.
The HDR stuff will be hit or miss, it’s backwards compatible in the sense that a viewer that doesn’t understand it will fall back to the ICC profile, but that still requires the viewer to support the (now deprecated) ICC based HDR method. If it doesn’t support HDR at all then you’re just out of luck since these images just require fundamentally different ways to view them.
