Multiple-image Network Graphics

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Multiple-image Network Graphics is a public graphics file format for animated images.

MNG is closely related to the PNG image format. When PNG development started in early 1995, developers decided not to incorporate support for animation, not least because this feature of GIF was seldom used at the time^{[citation needed]}. However, work soon started on MNG as an animation-supporting version of PNG. Version 1.0 of the MNG specification was released on January 31, 2001.

Application support

MNG is currently not as widely supported as PNG. Nonetheless, Konqueror and Gwenview have native MNG support, and MNG plugins are available for most other web browsers. Mozilla browsers and Netscape 6.0, 6.01 and 7.0 included native support for MNG until the code was removed in 2003 due to code size and little actual usage^[1], causing complaints on the Mozilla development site^[2]. As a result, a MNGzilla project was started to offer patched Mozilla and Firefox browsers. Neither Internet Explorer, Opera, nor Safari currently support MNG natively. Recent Sony Ericsson phones support MNG files in their themes. The Sphere game engine supports the use of MNG files for animations^[3]. GIMP can export images as MNG files. Imagemagick can create a MNG file from a series of PNG files. If MPlayer is linked against libmng, MPlayer and thus all graphical front-ends like KMPlayer and Gnome MPlayer can display MNG files.

The MNG developers hope that in time MNG will begin to replace GIF for animated images on the World Wide Web, just as PNG has already begun to do for still images.^[4] However, with the expiration of LZW patents and existence of alternative file formats such as Flash and SVG, combined with lack of MNG supporting viewers, web usages were far less than expected.

Technical details

The structure of MNG files is essentially the same as that of PNG files, differing only in the slightly different signature (8A 4D 4E 47 0D 0A 1A 0A in hexadecimal, where 4D 4E 47 is ASCII for "MNG" – see Portable Network Graphics: File header) and the use of a much greater variety of chunks to support all the animation features that it provides. Images to be used in the animation are stored in the MNG file as encapsulated PNG or JNG images.

Two versions of MNG of reduced complexity are also defined: MNG-LC (low complexity) and MNG-VLC (very low complexity). These allow applications to include some level of MNG support without having to implement the entire MNG specification, just as the SVG standard offers the "SVG Basic" and "SVG Tiny" subsets.

MNG does not yet have a registered MIME media type, but video/x-mng or image/x-mng can be used. MNG animations may be included in HTML pages using the <embed> or <object> tag.

MNG can either be lossy or lossless, depending whether the frames are encoded in PNG (lossless) or JNG (lossy).

Alternatives

GIF is often used. APNG is an alternative to MNG. Yet another alternative would be using animated SVG images with embedded PNG or JPEG graphics. Another option for the Web is to write JavaScript code that loads still PNG or JPEG images of each frame, and displays them one by one for a specified time interval. Apart from requiring the user to have JavaScript support and choose to enable it, this method can be CPU and bandwidth intensive for pages with more than one image, large images, or high framerates.

References

External links

• MNG Home Page
• List of browsers that support MNG images
• MNGzilla - An attempt to create a Mozilla variant that has MNG support included
• MNG testcases