During the spread of PNG, it took many web browsers a long time to fully support PNG format. For example, the default Internet Explorer browser of Microsoft Windows didn't support the translucent effect of PNG format until version 7.0. Earlier versions (such as 6.0 SP 1) needed to download hot fixes or websites provided additional scripts to support it, which led to the PNG format not being widely recognized.
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In the early period of 1995, Unisys began to collect commercial fees according to the software patent of LZW data compression algorithm in GIF format. In order to avoid the influence of patent, PNG representing a single image and MNG representing animation are created at the same time. 1In August, 1999, Unisys further suspended the GIF patent free license for free software and non-commercial software developers, which made PNG format get more attention.
1June, 1996, the draft of PNF (Portable Network Framework) was put forward, and it was renamed as MNG (Multi-image Network Graphics) in August of that year.
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