gif |
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Difino
| • | GIF (Graphics Interchange Format) is a bitmap image format for pictures that use 256 (or fewer) distinct colors (though there is a workaround for this limitation) and animations that use 256 (or fewer) distinct colors per frame. GIFs are compressed files, and are employed specifically to reduce the amount of time it takes to transfer images over a network connection. The format was introduced by CompuServe in 1987 and has since come into widespread usage on the World Wide Web. A GIF file employs lossless data compression so that the file size of an image may be reduced without degrading the visual quality (provided the image fits into 256 colors). The GIF format's 256-color limitation makes it unsuitable for photographs, though losslessly compressed photographs tend to be unacceptably large for the web anyway. On the other hand the lossy JPEG format does badly on sharp transitions like those in diagrams, producing highly visible artifacts and little file-size reduction. Therefore GIF is normally used for diagrams, buttons, etc., that have a small number of colors, while the JPEG format is used for photographs. Many software developers were caught by surprise when it was revealed that the GIF format had been patented by Unisys, and that they would have to pay royalties for writing programs that generated (or displayed) GIF files. The desire for a comparable format with fewer legal restrictions (as well as fewer technical restrictions such as the number of colours) led to the development of the PNG (Portable Network Graphics) standard. Although the GIF patents will expire in near future, PNG is still touted as a technically superior alternative, and has become the third most common image format on the web. The latest expiration date of the GIF related patents the most probably is Friday 11, August 2006 [HTTP ]. Source: [wikipedia: gif] |
2d:graphics
| Burn All GIFs | ||
| information on upgrading a web site from the patent-encumbered gif format to freely available graphics. | ||
 |
Graphics Interchange Format | |
| original specification describing the file layout as originated by compuserve. also known as gif87a. | ||
| US4558302 Patent | ||
| the us patent covering the lzw compression algorithm used in gif images. | ||
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