Fwd: Charter for a new PNG Working Group - please contact your AC Representative.

-------- Forwarded Message --------
Subject:  Charter for a new PNG Working Group - please contact your AC 
Representative.
Date:  Fri, 30 Jul 2021 16:56:37 +0300
From:  Chris Lilley <chris@w3.org>
To:  MEIG <"public-web-and-tv "@w3.org>, public-tt@w3.org, 
public-colorweb@w3.org <public-colorweb@w3.org>
CC:  Chairs <chairs@w3.org>, w3c-css-wg <w3c-css-wg@w3.org>, 
w3c-svg-wg@w3.org



Hello,

The Portable Network Graphics (PNG)  specification was published in 
2003, as both a W3C Recommendation and as an ISO Standard, with 
identical contents.

Since then, errata have accumulated and there has been no Working Group 
to maintain the specification.
https://github.com/w3c/PNG-spec/issues

Also in the interim, new requirements have arisen which could be added 
to the PNG specification without harming the excellent interoperability 
and backwards compatibility of existing images, image creation software 
and image consuming/display software.

A charter for a new WG to maintain and develop the PNG specification is 
under AC review
https://www.w3.org/Graphics/PNG/png-2021-ac.html

In particular, a new feature for support for HDR imagery to the PNG 
format 
<https://github.com/w3c/ColorWeb-CG/blob/master/hdr-in-png-requirements.md> 
is expected to be added. Also, the existing and widely implemented 
Animated PNG <https://wiki.mozilla.org/APNG_Specification> extensions, 
which were not part of the formal specification, are expected to be added.
https://github.com/w3c/ColorWeb-CG/blob/master/hdr-in-png-requirements.md
https://wiki.mozilla.org/APNG_Specification

APNG is already widely implemented, it is just a case of re-aligning the 
specification with implementations.

Adding HDR and WCG imaging support will use the existing ITU H.273 
metadata. This method is expected to be more interoperable, and also 
produce smaller files, than the previous method pioneered by the Timed 
Text WG.

There is also an existing eXif tag, for EXIF metadata, again widely 
supported but not part of the 2003 PNG specification.

Due to the age of the PNG spec, ICC v.2 is supported but ICC v.4 is not 
mentions. However it is widely supported in practice. Also, the 
description of the ICC profile is currently restricted to Latin-1 and 
needs to be extended to allow UTF-8. Again, the specification needs to 
align with implementations.

The plan is also to add Web Platform Test tests for all of the new features.

If you are interested in contributing to this work, or even just 
interested to see it move forward, please contact your AC Rep to let 
them know and to encourage their support in this review. Chairs, please 
forward to anyone in your groups who may be interested. The review 
period ends 23:59, Boston time on 2021-08-18.

I am happy to answer any questions on the technical proposals, or the 
scope of the proposed Group.

The review form (for AC Reps, only) is at
https://www.w3.org/2002/09/wbs/33280/png-2021/

-- 
Chris Lilley
@svgeesus
Technical Director @ W3C
W3C Strategy Team, Core Web Design
W3C Architecture & Technology Team, Core Web & Media