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

Fri Jun 20 10:28:10 PDT 2025

Good call, thank you for noting this John.

V/R Don

On Thu, Jun 19, 2025 at 22:38 John Carlson via x3d-public <
x3d-public at web3d.org> wrote:

> 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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