[x3d-public] Portable Network Graphics (PNG) Third Edition is a Proposed Recommendation

Thu Jun 19 22:37:20 PDT 2025

I’m guessing APNG will be used with MovieTexture.

John

On Thu, Jun 19, 2025 at 8:12 PM Brutzman, Donald (Don) (CIV) via x3d-public
<x3d-public at web3d.org> wrote:

> Wondering if anyone has been using PNG 3, which includes animation
> capabilities?
>
>
>    - *Portable Network Graphics (PNG) Specification (Third Edition)*
>    - W3C Proposed Recommendation 15 May 2025
>    - This document describes PNG (Portable Network Graphics), an
>    extensible file format for the 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, greyscale, and truecolor 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.
>    - https://www.w3.org/TR/png-3
>    Portable Network Graphics (PNG) Specification (Third Edition)
>    <https://www.w3.org/TR/png-3>
>    This document describes PNG (Portable Network Graphics), an extensible
>    file format for the 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, greyscale,
>    and truecolor images are supported, plus an optional alpha channel.
>    www.w3.org
>    **
>
>    - *PNG, Third Edition: Implementation Report*
>    - Includes list of implementation libraries and shows web-browser
>    support
>    - https://w3c.github.io/png/Implementation_Report_3e/
>    PNG, Third Edition: Implementation Report
>    <https://w3c.github.io/png/Implementation_Report_3e/>
>    Introduction. This report summarizes the implementation status of PNG,
>    Third Edition at the time of publication: in browsers, image authoring
>    tools, image viewers and other image utilities.. The changes in PNG Third
>    Edition, compared to the Second Edition are divided into new (or
>    newly-standardized) features, substantive changes to existing features, and
>    many editorial corrections and ...
>    w3c.github.io
>
>
> Of note there:
>
>    - *Animated PNG (APNG)*
>    - Although proposed in 2007 and widely implemented in browsers between
>    2009 and 2017, APNG had not been adopted by the ad-hoc group which produced
>    the early PNG specifications. PNG Third Edition retrospectively
>    standardizes this useful extension. APNG has a distinct Internet Media
>    type <https://w3c.github.io/PNG-spec/#image-apng> (MIME type)
>    registered and standardized in PNG Third Edition.
>
> Am expecting X3D implementers and modelers will be interested:
>
>
>    - Implementing and evaluation an ImageTexture capability for 3D
>    texturing as part of (at least 3) X3D players,
>    - X3DOM https://www.x3dom.org
>       - X_ITE      https://create3000.github.io/x_ite
>       - Castle   https://castle-engine.io/castle-model-viewer
>
>       - Listing PNG 3e as a normative requirement in draft X3D 4.1
>    Architecture, ISO/IEC 19775-1 which in turn affects multiple related
>    international standards for corresponding file formats and
>    programming-language bindings.
>    -
>       https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/Architecture.html
>       - Likely deserving upgrading: clause 18 Texturing component, 18.2.2
>       Texture map image formats
>       -
>       https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/components/texturing.html#TextureMapImageFormats
>
>
>
>    - Considering potential improved capabilities of PNG 3e in support of
>    3D Web Interoperability Working Group efforts in Metaverse Standards Forum
>    (MSF)
>    - https://metaverse-standards.org/domain-groups/3d-web-interoperability
>
>
> This seems like a major opportunity for X3D modeling and rendering
> capabilities.
>
> p.s. *History lesson learned: yes we can do it!*  Following release in
> 1987, then in the earliest days of the Web, use of Graphics Interchange
> Format (GIF) images was widespread.   After unfettered adoption for years,
> Unisys discovered that they had acquired patent rights and announced
> various plans to start charging royalties.  A number of programmers got
> together to determine requirements and independently create a "clean room"
> image format that was unencumbered by patents.  The result turned out to be
> technically superior in perhaps every respect (including image fidelity,
> compression, and performance), eventually becoming both a World Wide Web
> Consortium (W3C) Recommendation and an ISO International Standard.
>
>
>    - Wikipedia, GIF Alternatives: PNG
>    - Portable Network Graphics
>    <https://en.wikipedia.org/wiki/Portable_Network_Graphics> (PNG) was
>    designed as a replacement for GIF in order to avoid infringement of Unisys'
>    patent on the LZW compression technique.[42]
>    <https://en.wikipedia.org/wiki/GIF#cite_note-PNG-42> PNG offers better
>    compression and more features than GIF,[59]
>    <https://en.wikipedia.org/wiki/GIF#cite_note-png_fea-59> animation
>    being the only significant exception. PNG is more suitable than GIF in
>    instances where true-color imaging and alpha transparency
>    <https://en.wikipedia.org/wiki/Alpha_transparency> are required.
>    - Although support for PNG format came slowly, new web browsers
>    <https://en.wikipedia.org/wiki/Web_browser> support PNG.
>    - https://en.wikipedia.org/wiki/GIF#Alternatives
>
>
> Regarding PNG animation, further down that same page:
>
>
>    - APNG
>    <https://en.wikipedia.org/wiki/Animated_Portable_Network_Graphics> ("Animated
>    Portable Network Graphics") was proposed by Mozilla
>    <https://en.wikipedia.org/wiki/Mozilla> in 2006. APNG is an extension
>    to the PNG format as alternative to the MNG format. APNG is supported by
>    most browsers as of 2019.[63]
>    <https://en.wikipedia.org/wiki/GIF#cite_note-63> APNG provides the
>    ability to animate PNG files, while retaining backwards compatibility in
>    decoders that cannot understand the animation chunk (unlike MNG). Older
>    decoders will simply render the first frame of the animation.
>    The PNG group officially rejected APNG as an official extension on 20
>    April 2007.[64] <https://en.wikipedia.org/wiki/GIF#cite_note-64>
>    There have been several subsequent proposals for a simple animated
>    graphics format based on PNG using several different approaches.[65]
>    <https://en.wikipedia.org/wiki/GIF#cite_note-proposalcomparison-65> Nevertheless,
>    APNG is still under development by Mozilla and is supported in Firefox
>    3.0 <https://en.wikipedia.org/wiki/Mozilla_Firefox#Version_3.0>[66]
>    <https://en.wikipedia.org/wiki/GIF#cite_note-APNG-66>[67]
>    <https://en.wikipedia.org/wiki/GIF#cite_note-mozlabsapng-67> while MNG
>    support was dropped.[68]
>    <https://en.wikipedia.org/wiki/GIF#cite_note-68>[69]
>    <https://en.wikipedia.org/wiki/GIF#cite_note-69> APNG is currently
>    supported by all major web browsers including Chrome (since version 59.0),
>    Opera, Firefox and Edge.
>
>
> Bottom line:  *All X3D PNG3 examples, implementation reports, and
> open-source code welcome.*
>
> Thanks in advance for all efforts, shared lessons learned, and coolness.
>
> Have fun with X3D and PNG 3!  🙂
>
>
> all the best, Don
>
> --
>
> Don Brutzman  Naval Postgraduate School, Code USW/Br
> brutzman at nps.edu
>
> Watkins 270,  MOVES Institute, Monterey CA 93943-5000 USA
> +1.831.656.2149
>
> X3D graphics, virtual worlds, navy robotics
> https://faculty.nps.edu/brutzman
>
>
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