Type: Raster
    Extension: PNG
      Version: 
  Compression: RLE
  Color Depth: 1 to 48 bits
   Maintainer: Tom Boutell
Specification: http://www.boutell.com/boutell/png/

PNG (pronounced "ping"), Portable Network Graphics, is a new bitmap format
whose creation was spurred by the unfortunate legal situation surrounding
the GIF format.  The PNG specification explains its basic rationale thus:

  The PNG format provides a portable, legally unencumbered, well-compressed,
  well-specified standard for lossless bitmapped image files.  Although the
  initial motivation for developing PNG was to replace GIF, the design
  provides some useful new features not available in GIF, with minimal cost
  to developers.

The PNG specification is now frozen, and has been approved as a W3C
Recommendation by the World Wide Web Consortium.  It has also been
approved as an informational RFC, but (as of Jan 1997) has not yet been
formally issued by IETF.

Questions about PNG may be asked on the comp.graphics.misc newsgroup, or via
email at:

  png-info@uunet.uu.net

Several PNG-related mailing lists are available:

  png-list@dworkin.wustl.edu        General PNG discussion
  png-announce@dworkin.wustl.edu    Announcements related to PNG (low volume)
  png-implement@dworkin.wustl.edu   Discussion of PNG implementations

To find out more about the mailing list server, send mail to
png-list-request@dworkin.wustl.edu with the word "help" (and nothing else)
in the message body.

The official PNG FTP archive is:

  ftp://ftp.uu.net/graphics/png/

which is currently mirrored at

  ftp://swrinde.nde.swri.edu/pub/png/

The archives include the specification text in several formats (the spec
is also available from W3C at the URL cited above), a reference
implementation in portable C (still in development, as of 1996), and sets
of test images.  Note that in the case of any discrepancy between the
specification and the reference implementation, the specification is to be
considered correct and the code in error.

The PNG group has a home page with pointers to many other PNG resources at:

  http://www.wco.com/~png/

PNG's very first journal article has appeared:

  PNG: The Portable Network Graphic Format, Dr. Dobb's Journal, 
    Lee Daniel Crocker, #232 July 1995 (Vol 20, Issue 7), pp. 36-44.

The code for the above issues are available at:

  ftp://ftp.mv.com/pub/ddj/1995/1995.07/ptot.zip

And another article:

  Portable Network Graphics, Web Techniques, Paul Atzberger and 
    Andrew Zolli, Vol 1. Issue 9, December 1996, pp. 65-70.

See also MNG (Multiple Network Graphics)