"For the Web, PNG really has three main advantages over GIF: alpha channels (variable transparency), gamma correction (cross-platform control of image brightness), and two-dimensional interlacing (a method of progressive display). PNG also compresses better than GIF in almost every case, but the difference is generally only around 5% to 25%, not a large enough factor to encourage folks to switch on that basis alone. One GIF feature that PNG does not try to reproduce is multiple-image support, especially animations; PNG was and is intended to be a
This page is intended to provide an explanation of some of the features of the PNG format for non-technical users. As such, it doesn't emphasize PNG features like freedom from patents; those are more of concern to developers. Where programmer information is given, it is principally to explain to the user why various applications may not perform as well as expected. Where performance claims are made--especially compression comparisons with other image formats--we assume that the PNG implementation is at least as good as the best freeware encoders. Note
This page is intended to provide an explanation of some of the features of the PNG format for non-technical users. As such, it doesn't emphasize PNG features like freedom from patents; those are more of concern to developers. Where programmer information is given, it is principally to explain to the user why various applications may not perform as well as expected. Where performance claims are made--especially compression comparisons with other image formats--we assume that the PNG implementation is at least as good as the best freeware encoders. Note
Portable Network Graphic (PNG, pronounced "ping") is an image format developed by a consortium of graphic software developers as a nonproprietary alternative to the GIF image format. As mentioned earlier, CompuServe developed the GIF format, and GIF uses the proprietary LZW compression scheme owned by Unisys Corporation. Any graphics tool developer who makes software that saves in GIF format must pay a royalty to Unisys and CompuServe.
PNG graphics were designed specifically for use on Web pages, and they offer a range of attractive features that
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