Editing PNG (section)

== Software support ==
The official [[reference implementation]] of the PNG format is the [[library (computing)|programming library]] ''[[libpng]]''.<ref>{{cite web| url=http://libpng.org/pub/png/libpng.html| title=libpng| access-date=2013-07-13}}</ref> It is published as free software under the terms of a [[permissive free software license]]. Therefore, it is usually found as an important system library in free operating systems.

=== Bitmap graphics editor support for PNG ===
{{Main|Comparison of raster graphics editors}}

The PNG format is widely supported by graphics programs, including [[Adobe Photoshop]], [[Corel]]'s [[Corel Photo-Paint|Photo-Paint]] and [[Corel Paint Shop Pro|Paint Shop Pro]], the [[GIMP]], [[GraphicConverter]], [[Helicon Filter]], [[ImageMagick]], [[Inkscape]], [[IrfanView]], Pixel image editor, [[Paint.NET]] and [[Xara Photo & Graphic Designer]] and many others (including online graphic design platforms such as [[Canva]]). Some programs bundled with popular [[operating system]]s which support PNG include [[Microsoft]]'s [[Microsoft Paint|Paint]] and [[Apple Inc.|Apple]]'s [[Photos (Apple)|Photos]]/[[iPhoto]] and [[Preview (macOS)|Preview]], with the GIMP also often being bundled with popular [[Linux]] distributions.

[[Adobe Fireworks]] (formerly by [[Macromedia]]) uses PNG as its native file format, allowing other image editors and preview utilities to view the flattened image. However, Fireworks by default also stores metadata for layers, animation, vector data, text and effects. Such files should not be distributed directly. Fireworks can instead export the image as an optimized PNG without the extra metadata for use on web pages, etc.{{Citation needed|date=May 2012}}

=== Web browser support for PNG ===
{{Main|Comparison of web browsers#Image format support|l1=Web browser image format support}}
PNG support first appeared in 1997, in [[Internet Explorer]] 4.0b1 (32-bit only for NT), and in [[Netscape]] 4.04.<ref>{{cite web| url = http://oregon.usgs.gov/png_images.html| title = Use of PNG Images to Display Data| publisher = Oregon Water Science Center| date = 16 February 2006| access-date = 21 October 2003| archive-date = 20 August 2008| archive-url = https://web.archive.org/web/20080820132117/http://oregon.usgs.gov/png_images.html| url-status = dead}}</ref>

Despite calls by the [[Free Software Foundation]]<ref>{{cite web| url = https://www.gnu.org/philosophy/gif.html| title = Why There Are No GIF files on GNU Web Pages| work = [[GNU|GNU Operating System]]| date = 16 December 2008}}</ref> and the [[World Wide Web Consortium]] (W3C),<ref>{{cite web| url = http://www.w3.org/Press/PNG-fact.html| title = PNG Fact Sheet| publisher = [[World Wide Web Consortium]]| date = 7 October 1996}}</ref> tools such as gif2png,<ref>{{cite web|url=http://www.catb.org/~esr/gif2png/|title=Resource page for gif2png 2.5.11|work=catb.org}}</ref> and campaigns such as Burn All GIFs,<ref>{{cite web|url=http://burnallgifs.org/archives/|title=Burn All GIFs|website=burnallgifs.org}}</ref> PNG adoption on websites was fairly slow due to late and buggy support in Internet Explorer, particularly regarding transparency.<ref>{{cite magazine| url = https://www.pcmag.com/article2/0,2817,1645187,00.asp| title = PNG Transparency in Internet Explorer| magazine = [[PC Magazine]]| date = 5 October 2004}}</ref> PNG is the most used image file format on the web since 2018.<ref>{{cite web|url=https://w3techs.com/technologies/history_overview/image_format/all/y|title=Historical yearly trends in the usage statistics of image file formats for websites|website=w3techs.com}}</ref>

PNG compatible browsers include: Apple [[Safari (web browser)|Safari]], [[Google Chrome]], [[Mozilla Firefox]], [[Opera (web browser)|Opera]], [[Camino (web browser)|Camino]], [[Internet Explorer]], [[Microsoft Edge (series of web browsers)|Microsoft Edge]] and many others. For the complete comparison, see [[Comparison of web browsers#Image format support|Comparison of web browsers (Image format support)]].

Especially versions of Internet Explorer (Windows) below 9.0 (released 2011) had numerous problems which prevented it from correctly rendering PNG images.<ref name="png-msie">{{cite web| url = http://libpng.org/pub/png/pngapbr.html#msie-win-unix| title = Browsers with PNG Support| date = 14 March 2009}}</ref>

* 4.0 crashes on large PNG chunks.<ref>{{cite web| url = http://kb.adobe.com/selfservice/viewContent.do?externalId=tn_13501&sliceId=2| title = Windows Explorer Crashes When I Click on a Fireworks PNG File to View It| publisher = [[Adobe Systems]]| date = 5 June 2007}}</ref>
* 4.0 does not include the functionality to view .png files,<ref>{{cite web| url = http://support.microsoft.com/kb/174946| title = Unable to view .png images with Internet Explorer 4.0| work = Microsoft Knowledge Base}}</ref> but there is a registry fix.<ref name="png-msie" />
* 5.0 and 5.01 have broken OBJECT support.<ref>{{cite web| url = http://support.microsoft.com/kb/257081| title = PNGs That Are Inside of an Object Tag Print as a Negative Image| work = Microsoft Knowledge Base}}</ref>
* 5.01 prints palette images with black (or dark gray) backgrounds under Windows 98, sometimes with radically altered colors.<ref>{{cite web| url = http://support.microsoft.com/kb/255239| title = PNG Images Are Printed Improperly in Internet Explorer 5.01| work = Microsoft Knowledge Base}}</ref>
* 6.0 fails to display PNG images of 4097 or 4098 bytes in size.<ref>{{cite web| url = http://support.microsoft.com/kb/822071| title = You cannot view some PNG images in Internet Explorer 6| work = Microsoft Knowledge Base}}</ref>
* 6.0 cannot open a PNG file that contains one or more zero-length IDAT chunks. This issue was first fixed in security update 947864 (MS08-024). For more information, see this article in the Microsoft Knowledge Base: [http://support.microsoft.com/kb/947864/ 947864] MS08-024: Cumulative Security Update for Internet Explorer.<ref>{{cite web| url = http://support.microsoft.com/kb/897242| title = You cannot use Internet Explorer 6 to open a PNG file that contains one or more zero-length IDAT chunks| work = Microsoft Knowledge Base}}</ref>
* 6.0 sometimes completely loses ability to display PNGs, but there are various fixes.<ref>{{cite web| url = http://libpng.org/pub/png/pngfaq.html#msie| title = PNG Frequently Asked Questions}}</ref>
* 6.0 and below have broken alpha-channel transparency support (will display the default background color instead).<ref>{{cite web| url = http://support.microsoft.com/kb/265221| title = PhD: Portable Network Graphics Lose Transparency in Web Browser| work = Microsoft Knowledge Base}}</ref><ref>{{cite web| url = http://support.microsoft.com/kb/294714| title = PNG Files Do Not Show Transparency in Internet Explorer| work = Microsoft Knowledge Base}}</ref><ref>{{cite web| url = http://www.alistapart.com/articles/pngopacity/| title = Cross-Browser Variable Opacity with PNG: A Real Solution| first = Michael| last = Lovitt| work = [[A List Apart]]| date = 21 December 2002| access-date = 21 July 2009| archive-url = https://web.archive.org/web/20110818032515/http://www.alistapart.com/articles/pngopacity/| archive-date = 18 August 2011| url-status = dead}}</ref>
* 7.0 and below cannot combine 8-bit alpha transparency AND element opacity ([[Cascading Style Sheets|CSS]] – filter: Alpha (opacity=xx)) without filling partially transparent sections with black.<ref>{{cite web| url = http://channel9.msdn.com/forums/TechOff/257324-IE7-alpha-transparent-PNG--opacity/| title = IE7 alpha transparent PNG + opacity| work = [[Channel 9 (discussion forum)|Channel 9]]| access-date = 23 January 2009| archive-url = https://web.archive.org/web/20110827114121/http://channel9.msdn.com/forums/TechOff/257324-IE7-alpha-transparent-PNG--opacity| archive-date = 27 August 2011| url-status = dead}}</ref>
* 8.0 and below have inconsistent/broken gamma support.<ref name="png-msie"/>
* 8.0 and below don't have color-correction support.<ref name="png-msie"/>

=== Operating system support for PNG icons ===
PNG icons have been supported in most distributions of [[Linux]] since at least 1999, in desktop environments such as [[GNOME]].<ref>{{cite web| url = http://developer.gnome.org/doc/whitepapers/libroadmap/| title = GNOME 1.0 Library Roadmap| first = Michael| last = Fulbright| year = 1999| access-date = 19 December 2007| archive-url = https://web.archive.org/web/20100130042852/http://developer.gnome.org/doc/whitepapers/libroadmap/| archive-date = 30 January 2010| url-status = dead}}</ref> In 2006, [[Microsoft Windows]] support for PNG icons was introduced in [[Windows Vista]].<ref>{{cite web|url=http://www.oone.googlepages.com/windows_vista_icons.htm|title=Windows Vista – Icons|access-date=2007-11-12|work=OOne|year=2007|archive-date=11 November 2007|archive-url=https://web.archive.org/web/20071111153449/http://www.oone.googlepages.com/windows_vista_icons.htm|url-status=dead}}</ref> PNG icons are supported in [[AmigaOS 4]], [[AROS]], [[macOS]], [[iOS]] and [[MorphOS]] as well. In addition, [[Android (operating system)|Android]] makes extensive use of PNGs.