Mainstream Support and Present Status
If 1996 was the year of PNG's standardization, 1997 was the year of PNG
applications. After having taken over libpng development from Guy Eric Schalnat
in June 1996, Andreas Dilger shepherded it through versions 0.89 to 0.96,
adding numerous features and finding and fixing bugs; application
developers seemed not to mind the library's ``beta'' version number, and
increasingly employed it in their mainstream apps. With native support
in popular programs such as Adobe's Photoshop and Illustrator, Macromedia's
Freehand, JASC's Paint Shop Pro, Ulead's PhotoImpact, and Microsoft's
Office 97 suite, PNG's star was clearly rising. But perhaps the crowning
moment came in the autumn, with fresh versions of the Big Two web browsers.
Microsoft's Internet Explorer 4.0 in October and Netscape's Navigator 4.04
in November both included native, albeit somewhat limited, PNG support.
At last, the widespread use of PNG on the Web came within the realm of
possibility.
The theme for 1998 seems to have been maturity. Having been
handed the reins of principal libpng development at the beginning of
the year, Glenn Randers-Pehrson fixed many bugs, finished the
documentation and generally polished libpng into a stable release
worthy of a ``1.0'' version number by early March--three years to
the day, in fact, after the PNG specification was frozen. In February,
the UK Digital Television Group released the MHEG-5 UK Profile for
next-generation teletext on digital terrestrial television; the
profile included PNG as one of its bitmap formats, and as a result,
manufacturers such as Philips, Sony, Pace and Nokia were expected to
be shipping digital televisions and set-top boxes with built-in PNG
support by the time this book reaches print. At the very end of March 1998,
Netscape released Mozilla, the pre-alpha source code to Communicator
5.0, which allowed interested third parties (like the PNG Group) to
tinker with the popular browser and make it work as intended. In
October, the PNG Group approved some important additions and
clarifications to one of the more difficult technical aspects of the
PNG spec, namely, gamma and color correction; these changes defined
the PNG 1.1 specification--the first official revision in three and
a half years. And at roughly the same time, a joint committee of the
International Organization for Standardization (ISO) and the
International Electrotechnical Commission (IEC) began the yearlong
process to make Portable Network Graphics an official international
standard (to be known as ISO/IEC 15948 upon approval).
But a history bereft of darker events is perhaps not so interesting...and,
sadly enough, for a brief period in April 1998, it appeared that things
might once again be percolating on the legal front. Specifically, there
were rumors that Stac, Inc., believed the deflate compression engine in zlib
(which is used by libpng) infringed on two of their patents. Careful
reading of the patents in question, United States patents 4,701,745 and
5,016,009, suggests that although it is possible to write an infringing
deflate engine, the one actually used in zlib does not do so.[55]
Moreover, as this is written, a full year has passed with no public
claims from Stac, no further private contacts, and no confirmation of
the original rumors. However, until this is tested in court or Stac
makes a public announcement clearing zlib of suspicion, at least a
small cloud will remain over the Portable Network Graphics
format as a whole. The irony should be evident to one and all.
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