MAmarklit·Aug 5, 2025Submission
Consider using Zstandard and/or LZ4 instead of Deflate
191 points · Open discussionw3c
png
HTML2021–2025
w3c / png
png
Maintenance of the PNG specification
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Maintenance of the PNG specification
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This week on Hacker News
Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 5:04:57 PM UTC.
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HN mentions by year7 dated mentions
Observed mentions: 2021-12-16 02:39:41 UTC to 2025-08-05 17:18:37 UTC.
Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.
View mention counts and date ranges
| Period | Start (UTC) | End (exclusive, UTC) | Mentions | Submissions | Comments |
|---|---|---|---|---|---|
| 2021 | 2021-01-01 00:00:00 UTC | 2022-01-01 00:00:00 UTC | 2 | 0 | 2 |
| 2022 | 2022-01-01 00:00:00 UTC | 2023-01-01 00:00:00 UTC | 1 | 0 | 1 |
| 2023 | 2023-01-01 00:00:00 UTC | 2024-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2024 | 2024-01-01 00:00:00 UTC | 2025-01-01 00:00:00 UTC | 2 | 1 | 1 |
| 2025 | 2025-01-01 00:00:00 UTC | 2026-01-01 00:00:00 UTC | 2 | 1 | 1 |
What Hacker News says
7 sourcesBetter compression can also mean a new set of filter methods or a new interlacing algorithm. But yeah, any of them would cause an instant incompatibility. As noted in the relevant issue [1], we will need a new media type at the very least.
[1] https://github.com/w3c/png/issues/39#issuecomment-2674690324
In A new PNG specw3c/png: Consider using Zstandard and/or LZ4 instead of Deflate (2021)
3 points · Open discussionI don't know much about this proposal but I know that the restart marker proposal exists which I believe tries something very similar: https://github.com/w3c/png/issues/60
//EDIT: also Apple is assumed to have an extension that does something similar: https://www.hackerfactor.com/blog/index.php?/archives/895-Co...
In Parallel PNG Proposal (2021)fjxl is the "JXL_Lossless/f" lines in my full_benchmarks.txt link. It's about mid-table in terms of encode speed. I clocked it at about 10x faster than libpng, not 100x faster.
If you look solely at encode speed, fjxl loses to fpnge (also listed in full_benchmarks.txt) so I'm not convinced yet that JPEG XL beats PNG in all ways.
I believe that Apple have an unofficial PNG extension that facilitates multi-threaded decoding: https://github.com/w3c/PNG-spec/issues/45
In The case for JPEG XL> But its not like any reader ever supports it fully, hell most readers dont support showing the other images in a png file.
Do you mean APNG? In all fairness, that is not even in the specification although there is discussion to add it. https://github.com/w3c/PNG-spec/issues/26
The one that was specified was MNG but it was a different format and practically no one used it since it was not parsable as a PNG.
In QOI – The “Quite OK Image Format” for fast, lossless image compressionDecompressing zlib/DEFLATE streams, in the general case, is an inherently serial task. It cannot be meaningfully parallelised.
The "trick" used by Apple, and a few other encoders, is to flush the zlib state every so often (ZLIB_FULL_FLUSH), which means that subsequent data is both byte alligned, and does not make any backreferences to before the sync.
If you know where these sync points are (Apple encodes this information in their non-standard "iDOT" chunk) then you can start decompressing from that point, in an isolated thread.
There are ongoing discussions as to how this metadata could be standardised: https://github.com/w3c/PNG-spec/issues/54
In PNG Parser Differential