Editing PNG (section)

=== 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"/>