案例库 · 软件与 IT · 技术决策 · 1994–1996
这条还没译成中文，下面是英文原文。
PNG won the web's lossless image slot by being the one without a patent.
When Unisys demanded royalties on GIF's compression, developers built a royalty-free PNG, and its freedom plus lossless quality made it a lasting standard.
Thomas Boutell · the PNG development group · Unisys
那一手
GIF, released by CompuServe in 1987, used the Lempel-Ziv-Welch compression algorithm. Unisys owned the LZW patent, and in late 1994 it began insisting on royalties from developers who made GIFs, provoking a backlash across the free-software and web communities.
A working group led by Thomas Boutell set out to build a replacement with no patent in it, initially calling it PING for PING-if-not-GIF, later shortened to PNG. It fixed long-standing GIF weaknesses such as the lack of true 24-bit colour and added lossless compression and transparency.
The full specification was finalised in 1996 after approval by the World Wide Web Consortium, and the Free Software Foundation and W3C championed it. Browser support arrived from 1997, and PNG has since become one of the web's standard image formats.
为什么管用
- Being free of the LZW patent meant no developer had to pay or fear a lawsuit to use PNG.
- Lossless compression and millions of colours made PNG better than GIF for graphics, charts and logos.
- Real transparency was the feature web designers had been missing.
- Support from the W3C and the free-software world gave it an open-standards community behind it.
可以搬走什么
A format can win not by being cleverer but by being unencumbered - when a key component is licensed, the alternative that costs nothing to adopt gets the ecosystem.
后来呢
PNG became a core web image format alongside JPEG, favoured for logos, line art and anything with transparency. The GIF patent eventually expired, but PNG stayed because its patent-free, lossless design had already won the ecosystem.
资料来源
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