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A new PNG spec

programmax.net

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Re: A new PNG spec

#41

Post by mrheosuper »

danielheath wrote: post #37
mrheosuper wrote: post #26

Earlier quoted context omitted.

Does usb-c spec break backward compatibility ?, a 2018 macbook work perfectly fine with 2025 usb c charger

Some things don't work unless you use the right kind of USB-C cable. EG your GPU and monitor both have a USB-C port. Plug them together with the right USB cable and you'll get images displayed. Plug them together with the wrong USB cable and you won't. USB 3 didn't have this issue - every cable worked with every port.

That is not backward compatible problem. If a cable that does 100w charging when using pd2.0, but only 60w when using with pd3.1 device, then i would agree with you.

Re: A new PNG spec

#42

Post by mrheosuper »

techpression wrote: post #33
mrheosuper wrote: post #26

Earlier quoted context omitted.

Does usb-c spec break backward compatibility ?, a 2018 macbook work perfectly fine with 2025 usb c charger

I don’t know if it’s the spec or just a plethora of vendors that ignores it, but I have many things with a USB-C port that requires USB-A as source. USB-C to A to C works, yay dongles, but not just C to C. So maybe it’s not really breaking backwards compatibility, just a weird mix of a port and the communication being separate standards.

because those usb-c ports do not follow the spec. If they had followed the spec from 1st day there would be no problem even now.

Re: A new PNG spec

#43

Post by shakna »

andsoitis wrote: post #8
albert_e wrote: post #5

So animated GIFs can be replaced by Animated PNGs with alpha blending with transparent backgrounds and lossless compression! Some nostalgia from 2000s websites can be revived and relived :) Curious if Animated SVGs are also a thing. I remember seeing some Javascript based SVG animations (it was a animated chatbot avatar) - but not sure if there is any standard framework.

> Curious if Animated SVGs are also a thing. Yes. Relevant animation elements: • • • • See https://www.w3schools.com/graphics/svg_animation.asp

Slightly related, I recently hit on this SVG animation bug in Chrome (that someone else found):

https://shkspr.mobi/blog/2025/06/an-annoying-svg-animation-b...

Re: A new PNG spec

#44

Post by layer8 »

riffraff wrote: post #12
albert_e wrote: post #5

So animated GIFs can be replaced by Animated PNGs with alpha blending with transparent backgrounds and lossless compression! Some nostalgia from 2000s websites can be revived and relived :) Curious if Animated SVGs are also a thing. I remember seeing some Javascript based SVG animations (it was a animated chatbot avatar) - but not sure if there is any standard framework.

I was under the impression many gifs these days are actually served as soundless videos, as those basically compress better. Can animated PNG beat av1 or whatever?

APNG would be for lossless compression, and probably especially for animations without a constant frame rate. Similar to the original GIF format, with APNG you explicitly specify the duration of each individual frame, and you can also explicitly specify looping. This isn’t for video, it’s more for Flash-style animations, animated logos/icons [0], or UI screen recordings.

[0] like for example these old Windows animations: https://www.randomnoun.com/wp/2013/10/27/windows-shell32-ani...

Re: A new PNG spec

#45

Post by ggm »

SchemaLoad wrote: post #39
ggm wrote: post #14

Somebody needs to manage human time/date approximates in a way other people in s/w will align to. "photo scanned in 2025, is about something in easter, before 1940 and after 1920"

The issue that gets me is that Google Photos and Apple photos will let you manually pick a date, but they won't actually set it in the photo EXIF, so when you move platforms. All of the images that came from scans/sent without EXIF lose their dates.

It's in sidecar files. Takeout gets them, some tools read them.

Re: A new PNG spec

#46

Post by pvorb »

Lerc wrote: post #15
LeoPanthera wrote: post #3

> 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.

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.

Extending the format just because you can – and breaking backwards compatibility along the way – is even more pointless.

If you've created an extensible file format, but you never need to extend it, you've done everything right, I'd say.

Re: A new PNG spec

#47

Post by yoz-y »

mrheosuper wrote: post #41
danielheath wrote: post #37

Earlier quoted context omitted.

Some things don't work unless you use the right kind of USB-C cable. EG your GPU and monitor both have a USB-C port. Plug them together with the right USB cable and you'll get images displayed. Plug them together with the wrong USB cable and you won't. USB 3 didn't have this issue - every cable worked with every port.

That is not backward compatible problem. If a cable that does 100w charging when using pd2.0, but only 60w when using with pd3.1 device, then i would agree with you.

The problem is not backward compatibility but labeling. A USB-C cable looks universal but isn’t. Some of them just charge, some do data, some do PD, some give you access to high speed. But there is no way to know.

I believe the problem here is that you will have PNG images that “look” like you can open them but can’t.

Re: A new PNG spec

#48

Post by ggm »

luguenth wrote: post #40
ggm wrote: post #14

Somebody needs to manage human time/date approximates in a way other people in s/w will align to. "photo scanned in 2025, is about something in easter, before 1940 and after 1920"

In EXIF, you have DateTimeDigitized [0] For ambiguous dates there is the EDTF Spec[1] which would be nice to see more widely adopted. [0] https://www.media.mit.edu/pia/Research/deepview/exif.html [1] https://www.loc.gov/standards/datetime/

I remember reading about this in a web forum mainly for dublin core fanatics. Metadata is fascinating.

Different software reacts in different ways to partial specifications of yyyy/mm/dd such that you can try some of the cute tricks but probably only one s.w. package honours it.

And the majors ignore almost all fields other than a core set of one or two, disagree about their semantics, and also do wierd stuff with file name and atime/mtime.

Re: A new PNG spec

#49

Post by mystifyingpoi »

mrheosuper wrote: post #26
LeoPanthera wrote: post #3

> 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.

Does usb-c spec break backward compatibility ?, a 2018 macbook work perfectly fine with 2025 usb c charger

Yeah, I also don't think they've broken backwards compat ever. Super high end charger from 2024 can charge old equipment from 2014 just fine with regular 5V.

What was broken was the promise of a "single cable to rule them all", partly due to manufacturers ignoring the requirements of USB-C (missing resistors or PD chips to negotiate voltages, requiring workarounds with A-to-C adapters), and a myriad of optional stuff, that might be supported or not, without a clear way to indicate it.

Re: A new PNG spec

#50

Post by bmacho »

albert_e wrote: post #5

So animated GIFs can be replaced by Animated PNGs with alpha blending with transparent backgrounds and lossless compression! Some nostalgia from 2000s websites can be revived and relived :) Curious if Animated SVGs are also a thing. I remember seeing some Javascript based SVG animations (it was a animated chatbot avatar) - but not sure if there is any standard framework.

> Curious if Animated SVGs are also a thing.

SVG is just html5, it has full support for CSS, javascript with buttons, web workers, arbitrary fetch requests, and so on (obviously not supported by image viewers or allowed by browsers).

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