[transition] PR Request for Portable Network Graphics (PNG) Specification (Third Edition) - png-3

PR Request for Portable Network Graphics (PNG) Specification (Third Edition) - png-3
from https://github.com/w3c/transitions/issues/716

# Document title, URLs, estimated publication date
Portable Network Graphics (PNG) Specification (Third Edition)
https://www.w3.org/TR/png-3/
Once approved, and exclusion opportunity allows

# Abstract

This document describes PNG (Portable Network Graphics), an extensible file format for the [lossless](https://www.w3.org/TR/png-3/#dfn-lossless), portable, well-compressed storage of static and animated raster images. PNG provides a patent-free replacement for GIF and can also replace many common uses of TIFF. [Indexed-color](https://www.w3.org/TR/png-3/#3indexedColour), [greyscale](https://www.w3.org/TR/png-3/#dfn-greyscale), and [truecolor](https://www.w3.org/TR/png-3/#3truecolour) images are supported, plus an optional alpha channel. Sample depths range from 1 to 16 bits.

PNG is designed to work well in online viewing applications, such as the World Wide Web, so it is fully streamable with a progressive display option. PNG is robust, providing both full file integrity checking and simple detection of common transmission errors. Also, PNG can store color space data for improved color matching on heterogeneous platforms.

This specification defines two Internet Media Types, image/png and image/apng.

# Status
https://www.w3.org/TR/png-3/#sotd (as CR Snapshot)

# Will new features be allowed to be incorporated in the Recommendation?
No

# Link to group's decision to request transition
[CfC in progress, finishes 23 April](https://github.com/w3c/png/issues/512)

# Changes
**No changes** since CR Snapshot of 13 March 2025

# Requirements satisfied
No change in requirements

# Dependencies met (or not)
- [Normative References](https://www.w3.org/TR/png-3/#normative-references) do not contain any CR or WD

# Wide Review
_list identical to the CR Snapshot wide review_
 - https://github.com/w3c/png/issues/228
 - [Explainer](https://github.com/w3c/png/blob/main/Third_Edition_Explainer.md) used for TAG review
 - Some original PNG specification authors contributing, including becoming IE
 - [libpng](https://github.com/pnggroup/libpng) has shipped support for Third Edition chunks; increased collaboration with PNG WG
 - pnggroup officially adopted [pngcheck](https://github.com/pnggroup/pngcheck)
 - working with [ISO TC 42](https://www.iso.org/committee/48420.html)/WG 23, [Class C liaison](https://www.w3.org/liaisons/#I) in progress
 - Referenced by forthcoming ISO 21496-1 which wants to see it as W3C Recommendation asap
 - Liaison with SMPTE resulted in several SMPTE specifications, normatively referenced by PNG, becoming freely available at our request
 - [libspng](https://libspng.org/) is waiting for 3rd Edition to become a W3C Recommendation before adding support

# Issues addressed
 - [PNG 3rd Edition issues](https://github.com/w3c/png/issues?q=is%3Aissue%20state%3Aopen%20milestone%3A%223rd%20edition%22)

# Formal Objections
None

# Implementation
**Very** widely implemented - [Implementation Report](https://w3c.github.io/png/Implementation_Report_3e/)

# Patent disclosures
None
[Call for exclusion](https://www.w3.org/mid/cfe-15229-9243106cf3cdb8d3c5b6611ad1f2323885a18d9d@w3.org) started on 2025-03-13, opportunity until 2025-05-12



-- 
This email was generated automatically using https://github.com/w3c/transition-issues-bot

Received on Monday, 21 April 2025 18:05:16 UTC