A new PNG spec - Hacker News

Posted by bluedel 7 days ago

667 points | 598 commentspage 4

meindnoch 6 days ago|

Parallel compression/decompression is already possible via Z_SYNC_FLUSH.

Retr0id 6 days ago|

Parallel decompression of Z_SYNC_FLUSH'd data is not possible without additional metadata to tell you where the sync points are.

meindnoch 6 days ago||

True. Although this can be mitigated in a backwards compatible manner, by adding a new PNG chunk that points to the locations of the sync points.

Retr0id 6 days ago||

Yes, such a chunk is being considered for introduction in future PNG revisions.

nashashmi 5 days ago||

Time is ripe for audio-included animated PNG files.

naikrovek 6 days ago||

Doesn’t PNG already support 16 bits per color channel and an arbitrary number of color channels?

ProgramMax 6 days ago|

16-bit, yes. Arbitrary channel count, no. However, HDR is more than just bitcount.

kumarvvr 6 days ago||

Never heard about Animated PNGs, and I am a nerd to the core.

Pleasantly surprised.

spauldo 4 days ago|

Animation was an early feature, actually. It was called "MNG" and was developed alongside PNG. I don't know the details of why but it never really saw adoption outside of Firefox and was eventually removed even from there. APNG is different from MNG and came much later.

ccarnino 6 days ago||

I can't believe the standard is 20yo.

sylware 6 days ago||

Until everything new is "optional". Hopefully PNG won't be the target of "enshitification". We all know that for file formats, there is a very strong pressure from developers and vendors for that to happen since it favors, hard, vendor and developer lock-in. If not careful, even with a team of PHD devs won't be able to write alternatives encoders/decoders that "reasonbly" and the world will end-up with very few alternatives implementations, if not only one.

I did skim through the specs, it seems most of it is related to cleanup and optional blocks, so it seems PNG is still safe, am I wrong? (asking those who did dive into the new specs deeply).

ProgramMax 6 days ago|

Everything new is optional. This is not a breaking change. Old PNGs and software continue to work just fine. And these new changes are backwards-compatible as much as they can be. So old software can display a new PNG and be mostly correct. By that I mean, the user will still say "it is a picture of a red apple". But if the software isn't HDR, they might not get the bright highlights and inky blacks of the HDR PNG.

sylware 5 days ago||

What is the remaining pertinent value of HDR since we are moving towards xrgb16161616 pixel format?

defraudbah 6 days ago||

this is good news, any packages who support new png standard or planning to? rust/go/python/js?

NotAnOtter 6 days ago||

Can someone TLDR why I should care as someone who doesn't directly get into the weeds of this type of things?

Is this written exactly for (1) people who implement/maintain this and, I say this with love, (2) nerds. Or will there be effects outside of a microscopic improvement on storage + latency.

spauldo 4 days ago|

If you don't do much with images it's probably not anything you need to worry about. If you care about things like HDR, it means you can now use PNGs for that. If you work with graphics for a living, it's probably a good idea to learn what's changed in the standard.

PNG was a huge deal when it was new, mostly because of all the headaches Unisys was giving everyone over GIF compression patents. This new standard is mostly of interest to people that have reason to care about what format their image data is in.

leviathan1 6 days ago||

Not backwards compatible I think

ProgramMax 6 days ago|

It is very backwards compatible. :) We worked hard to make sure it would be.

aizk 6 days ago|

20 years?? What took so long.

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