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A new PNG spec

(www.programmax.net)
618 points bluedel | 3 comments | 24 Jun 25 13:01 UTC | HN request time: 0.659s | source
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LeoPanthera ◴[25 Jun 25 05:06 UTC] No.44373778[source]▶
> I know you all immediately wondered, better compression?. We're already working on that.

This worries me. Because presumably, changing the compression algorithm will break backwards compatibility, which means we'll start to see "png" files that aren't actually png files.

It'll be like USB-C but for images.

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Lerc ◴[25 Jun 25 05:35 UTC] No.44373928[source]▶
It has fields to say what compression is used. Adding another compression form should be handled by existing software as recognizing it as a valid PNG that they can't decompress.

The PNG format is specifically designed to allow software to read the parts they can understand and to leave the parts they cannot. Having an extensible format and electing never to extend it seems pointless.

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1. HelloNurse ◴[25 Jun 25 07:26 UTC] No.44374528[source]▶
Extensibility of PNG has been amply used, as intended, for proprietary chunks that hold application specific data (e.g. PICO-8 games) without bothering other software.
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2. Lerc ◴[25 Jun 25 13:24 UTC] No.44377066[source]▶
Doesn't pico-8 store the data in the least significant bits of colour? Maybe it got updated to use chunks.
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3. HelloNurse ◴[26 Jun 25 07:42 UTC] No.44385138[source]▶
Yes, my mistake. I assumed common sense.

https://pico-8.fandom.com/wiki/P8PNGFileFormat

Actual cases of proprietary chunks include iDOT from Apple (apparently a performance optimization for plain images)

https://www.hackerfactor.com/blog/index.php?/archives/895-Co...

and the Macromedia Fireworks save files

https://stackoverflow.com/questions/4242402/the-fireworks-pn...