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APNG

From Wikipedia, the free encyclopedia
For other uses, seeAPNG (disambiguation).
Animated PNG
An animated PNG, or APNG, of a bouncing ball (displays as static image insome web browsers)
Filename extension
.png,.apng
Internet media type
image/png,image/apng,image/vnd.mozilla.apng
Developed byMozilla Foundation(adopted byW3C)
Initial releaseAugust 27, 2004;19 years ago(2004-08-27)[1]
Type of formatanimatedlosslessbitmapimage
Extended fromPNG
Open format?yes

Animated Portable Network Graphics(APNG) is afile formatwhich extends thePortable Network Graphics(PNG) specification to permitanimatedimages that work similarly to animatedGIFfiles, while supporting 24 or 48-bit images andfull Alpha transparencynot available for GIFs. It also retainsbackward compatibilitywith non-animated PNG files.

The firstframeof an APNG file is stored as a normal PNG stream, so most standard PNG decoders are able to display the first frame of an APNG file. The frame speed data and extra animation frames are stored in extra chunks (as provided for by the original PNG specification). APNG competed withMultiple-image Network Graphics(MNG), a comprehensive format for bitmapped animations which was created by the same team as PNG and is obsolete. APNG's advantage was the smaller library size and compatibility with older PNG implementations.

History and development[edit]

An APNG of anMRIscan of a human head

The APNG specification was created in 2004 by Stuart Parmenter andVladimir Vukićevićof theMozilla Corporationto allow for storing the animations needed for interfaces such asthrobbers.[1][2]In May 2003, Mozilla had scrapped support forMNGanimations, which provides a superset of APNG functionality, citing concerns about the large file size required for the expansive MNG decoder library (300 KB);[3]the APNG decoder, built on the back of the PNG decoder, was a much smaller component.

Among users and maintainers of the PNG and MNG formats, APNG had a lukewarm reception. In particular, PNG was conceived to be a single-image format.[4]APNG hides the subsequent frames in PNG ancillary chunks in such a way that APNG-unaware applications would ignore them, but there are otherwise no changes to the format to allow software to distinguish between animated and non-animated images. Some of the main concerns arising from this were the inability of applications to negotiate for PNG and APNG, or distinguish between PNG and APNG once received, or for legacy software to even inform users that there are additional frames. Glenn Randers-Pehrson spearheaded efforts to reconcile the PNG purists' position with that of APNG proponents by recommending changes to APNG's format and proposing the use of a uniqueMIME type(e.g., video/png), but the APNG proponents only added the different MIME type (image/apng)[5]while insisting on the use of the.pngextension instead of.apng,leading to the format not being approved by the PNG Development Group.[6]

The PNG Development Group rejected APNG as an official extension on April 20, 2007,[7]and there have been several subsequent proposals for a simple animated graphics format based on PNG using several different approaches.[8]However, since September 14, 2021, the PNG Working Group has been charted by theWorld Wide Web Consortium(W3C) to maintain and develop for the PNG specification, and the first public working draft of PNG Specification (Third Edition) was published on October 25, 2022, adding APNG extensions to the core PNG specification.[9]The Candidate Recommendation was published on September 21, 2023.[10]

File format[edit]

The APNG specification follows thePNG File formatintroducing three new ancillary chunks:[11]

  • The animation control chunk (acTL) precedes the IDAT(s) of the default image and is a kind of "marker" that this is an animated PNG file. It also contains the number of frames and the number of times to loop the animation (0 meaning infinite).
  • The frame control chunk (fcTL) precedes each frame and contains its metadata: dimensions; position (relative to the default image); duration; if once over it is cleared to black, replaced by the previous frame or drawn over by the next frame; and if its transparency applies.
  • The frame data chunk (fdAT) storing frame's content. It starts with a sequence number, then has the same structure as the default image's IDAT chunk(s).

Sequence numbers apply to both frame control and frame data chunks, which together follow a common sequence, thus enabling the order and timing of frames to be recovered should an APNG-unaware PNG editor re-order them as allowed by PNG chunk ordering rules.[12]

Frames utilize the same bit depth, color type, compression method, filter method, interlace method, and palette (if any) as the default image.

An application reading a PNG file is meant to ignore any chunks which it does not understand,[13]making APNGbackwards compatible.Applications without support for the APNG extension show only the first frame, disregarding additional animation frames.

Diagram illustrating a possible way to assemble an animated PNG from three individual PNG files

Compression and Optimization[edit]

A number of optimization techniques make APNG files as small as possible:Inter-frameoptimization[14]utilizingAlpha -blendand Alpha dispose operations, smaller than the full-size subframes, dirty transparency, color type andcolor paletteoptimizations, and various compression options:zlib,7-Zip,Zopfli.[15]

Derived formats[edit]

AnimatedstickersforSignalare APNG with some restrictions (the size of the file is limited to 300kb, the length of the animation is limited to 3 seconds and, visibly (this last point is unclear), the resolution must be 512x512px).[which?][16]

Support[edit]

See also:Comparison of web browsers § Image format support
The logo of APNG Assembler,free softwareto create APNG images

Mozilla Firefoxadded support for APNG inversion 3trunk builds on March 23, 2007.[17]However, because libpng is the PNG Group'sreference implementationof the official specification, APNG support can never be supported in the main libpng distribution so long as it remains unratified by the Group.Iceweasel 3supports APNG by using Mozilla's unofficial variant of libpng.[18]

In 2008WorldDMBadopted APNG as a backward compatible extension to enable animation as part of the MOT SlideShow user application for Digital Radio. "APNG 1.0 Specification - Animated Portable Network Graphics" is included as normative Annex A in theETSIstandard TS 101 499 V2.2.1.[19]In 2016,Appleadopted the APNG format as the preferred format for animated stickers iniOS 10iMessageapps.[20]On March 15, 2017, APNG support was added toChromium.[21]

List of computer programs and their support of APNG, along with their version numbers and release date
Field Software Supports? Since
Image
processing 		APNG Assembler Yes v. 1[22]
cphktool APNG Anime Maker Yes v. 1 (9 June 2009)[23]
APNG Disassembler Yes v. 1[24]
APNG Optimizer Yes v. 1.0 (28 March 2011)[25]
Chasys Draw IES Yes[26] v. 5.17.05[27]
Clip Studio Paint Yes v. 1.6.7 (7 September 2017)[28]
FFmpeg Yes[29] v. 2.7[30]
FireAlpaca[ja] Yes v. 2.3.13[31]
Gamani GIF Movie Gear Yes v. 4.2 (March 2008)[32]
GID Read-only v. 11 (December 2023)[33]
GIMP Needs plug-in[34] —
Honeycam Yes v. 3.48 (29 November 2021)[35]
Honeyview Yes v. 5.10 (17 February 2015)[36]
ImageJ Yes v. 1.41g (3 July 2008)[37]
ImageMagick Yes v. 7.0.10-31 (20 September 2020)[38]
Imagine Yes v. 1.0.2 (4 May 2008)[39]
IrfanView Read-only v. 4.40 (31 July 2015)
Konvertor Yes v. 4.02 (May 2010)[40]
KSquirrel (later SAIL) Read-only v. 0.7.2 (3 October 2007)[41]
Paint.NET Needs plugin[42] —
PhotoLine Yes v19.5 (11 March 2016)
RealWorld Paint Yes v. 2011.1 (December 2011)[43]
VirtualDub Needs plugin[44][a] —
XnView Read-only v. 1.97.4 (30 April 2010)[45]
Sciter and HTMLayout UI engines Read-only since 2008
Krita Yes[46] Krita Nightly 5.0.0 pre- Alpha (since 22 February 2021)[47]
qView Read-only v. 4.0 (31 October 2020)
Browser
engines 		WebKit Yes (17 March 2015)[48]
Blink Yes June 2017
Web
browsers 		Mozilla Firefox
(Gecko layout engine) 		Yes v. 3 (17 June 2008)[49][50]
SeaMonkey
(Gecko layout engine) 		Yes v. 2
Iceweasel and other Debian rebrandings
(Gecko layout engine) 		Yes v. 4.0~b12[18]
Safari
(WebKit layout engine) 		Yes v. 8.0[51]
Google ChromeandChromium
(Blink layout engine) 		Yes v. 59 (5 June 2017)[52][53]
Internet Explorer
(Trident layout engine) 		No[51] —
Microsoft Edge
(EdgeHTML layout engine) 		No[51][54] —
Microsoft Edge
(Blink layout engine) 		Yes v. 79
Operav12 and earlier
(Presto layout engine) 		Yes v. 9.5 (12 June 2008)[55]
Opera15 and later
(Blink layout engine) 		Yes v. 46.0 (22 June 2017)[56]
Pale Moon(Goanna layout engine) Yes v. 27
Mobile
browsers 		iOSSafari Yes[51] v. 8.0
Firefox for Android Yes[51] ?
Samsung Internet for Android Yes v. 7.0
Opera Mobile Yes[citation needed] ?
Productivity
software 		LibreOffice Yes[57] Planned
  1. ^After loading a video, an APNG file can be created via the "File|Export|Animated PNG" menu item.

A server-side library exists that allows web browsers that support thecanvas tag,but do not support APNG, to display APNGs.[58]Examples of such browsers include Microsoft Edge and Internet Explorer 9.

See also[edit]

References[edit]

  1. ^ab"Add APNG support for Mozilla".Bugzilla.Mozilla Foundation. 27 August 2004.Retrieved23 April2024.
  2. ^Stuart Parmenter; Vladimir Vukicevic (2 September 2004)."APNG 0.4 [DRAFT]".Vladimir Vukicevic. Archived fromthe originalon 19 November 2004.Retrieved23 April2024.
  3. ^martin (1999-11-11)."Bug 18574 - (mng) restore support for MNG animation format and JNG image format".Mozilla.Retrieved2010-03-30.
  4. ^"PNG (Portable Network Graphics) Specification, Version 1.1#8.4. Multiple-image extension".libpng.Retrieved2010-03-30.
  5. ^"APNG Specification, Version 1.0#MIME type".Mozilla.Retrieved2017-12-10.
  6. ^"ImageMagick can't detect animated PNG".GitHub.Retrieved2017-12-10.
  7. ^"VOTE FAILED: APNG 20070405a".SourceForgemailing list. 2007-04-20.
  8. ^"Discussion for a simple" animated "PNG format".Archived fromthe originalon 2009-02-26.Retrieved2011-07-12.
  9. ^"PNG Third Edition, Explained".W3C GitHub.2023-05-24.
  10. ^"PNG Specification (Third Edition), APNG: frame-based animation".w3.org.2023-09-21.
  11. ^"APNG Specification - MozillaWiki".
  12. ^Chunk Ordering Rules(PNG 1.2 spec)
  13. ^"Portable Network Graphics (PNG) Specification (Second Edition)".
  14. ^"Inter-frame Optimization in APNG".littlesvr.ca.Archivedfrom the original on 2014-04-26.Retrieved2021-10-21.
  15. ^"APNG Assembler".apngasm.sourceforge.net.Retrieved2021-10-21.
  16. ^"Stickers".Signal Support.Signal.Retrieved28 December2021.
  17. ^"Gran Paradiso Alpha 3 release notes".Mozilla.2007-03-23. Archived fromthe originalon December 26, 2009.Retrieved2010-03-30.
  18. ^ab"Debian Bug #486827 Iceweasel cannot render APNG image".Debian.2011-08-26.Retrieved2011-09-18.
  19. ^"Digital Audio Broadcasting (DAB); MOT SlideShow; User Application (pdf) Specification"(PDF).ETSI.Retrieved30 January2013.
  20. ^"Messaging - Extensions - iOS Human Interface Guidelines".developer.apple.Apple, Inc.Retrieved2016-10-12.
  21. ^"Anzwix / Chromium / Add support for Animated PNG".Retrieved2017-03-15.
  22. ^maxst (15 November 2017)."APNG Assembler".SourceForge.
  23. ^"cphktool APNG Anime Maker".cphktool. Archived fromthe originalon 2010-02-09.Retrieved2010-06-28.
  24. ^maxst."APNG Disassembler".SourceForge.
  25. ^maxst."APNG Optimizer".SourceForge.
  26. ^"Online Help for Chasys Draw IES: File Formats - Other Image Files".
  27. ^"Online Help for Chasys Draw IES: History".Retrieved2022-07-18.
  28. ^"CLIP STUDIO PAINT Version 1.6.7 release notes (9/7/2017)".Retrieved2024-04-22.
  29. ^"FFmpeg Formats Documentation".
  30. ^"GitHub changelog of FFmpeg".GitHub.Retrieved2016-07-09.
  31. ^"FireAlpaca Update History".Retrieved2021-09-04.
  32. ^"Animated PNG: Simple Animation with an Alpha Channel".Gamani.Retrieved2009-08-25.
  33. ^"GID (Generic Image Decoder)".GitHub.Retrieved2023-12-09.
  34. ^"APNG Plug-In".Archived fromthe originalon 2014-05-25.Retrieved2010-05-28.
  35. ^"Honeycam - Version history".Bandisoft International Inc.Retrieved2022-01-09.
  36. ^"Honeyview - Version history".Bandisoft International Inc.Retrieved2022-01-09.
  37. ^"ImageJ News".ImageJ.Archivedfrom the original on May 21, 2009.Retrieved2009-05-23.
  38. ^"ImageMagick - Changelog".Retrieved2021-04-25.
  39. ^"Imagine - What's new".Archivedfrom the original on October 8, 2011.Retrieved2017-09-01.
  40. ^"Konvertor - Solutions for Multimedia Processing".Archived fromthe originalon 2010-05-12.Retrieved2010-05-19.
  41. ^"KSquirrel Codecs ChangeLog".GitHub.15 October 2021.
  42. ^"Animated Image 2.4 - AGIF & APNG".Paint.NET Forum.10 January 2009.
  43. ^"More about animated PNG - Vlasta's blog".rw-designer.
  44. ^"SourceForge.net: VirtualDub APNG Mod".vdubapngmod.sourceforge.net.
  45. ^While XnView is available for several operating systems, only versions forWindowshave been released since APNG support was added.
  46. ^"APNG export support".Retrieved2021-08-16.
  47. ^"APNG and WEBP animation export (dbe993da) · Commits · Graphics / Krita".GitLab.22 February 2021.Retrieved2021-08-16.
  48. ^"Animated PNG graphics".WebKit.Mar 17, 2015.Retrieved2015-03-17.
  49. ^Parmenter, Stuart; Vladimir Vukicevic; Andrew Smith (July 4, 2008)."Animated PNG graphics".Mozilla Developer Center.Mozilla.Archived fromthe originalon 2008-12-04.Retrieved2009-05-23.
  50. ^"Firefox 3 for developers".Mozilla Developer Center.Mozilla.October 1, 2008. Archived fromthe originalon 2008-11-13.Retrieved2009-05-23.
  51. ^abcde"Animated PNG (APNG)".Can I use... Support tables for HTML5, CSS3, etc.
  52. ^"7d2b8c45afc9c0230410011293cc2e1dbb8943a7 - chromium/src - Git at Google".chromium.googlesource.
  53. ^"Stable Channel Update for Desktop".Chrome Releases.Retrieved2017-06-06.
  54. ^"The status of APNG image format in Microsoft Edge".Microsoft Edge Development.Retrieved2017-07-29.
  55. ^"Web specifications supported in Opera 9.5".Opera Software.Archived fromthe originalon 2009-02-25.Retrieved2009-05-23.
  56. ^"Opera 46 goes final, more quality and Opera's first TV ad".Opera Software.22 June 2017.Retrieved2017-06-26.
  57. ^"Projects selected for LibreOffice in the Google Summer of Code 2023: Add APNG import/export support".LibreOffice.29 May 2023.Retrieved2023-05-29.
  58. ^"APNG-canvas Library".GitHub.11 October 2021.

External links[edit]

Wikimedia Commons has media related toAnimated PNG files.
Retrieved from "https://en.wikipedia.org/w/index.php?title=APNG&oldid=1227193708"