Information AboutGif |
| CATEGORIES ABOUT GRAPHICS INTERCHANGE FORMAT | |
| graphics file formats | |
| compuserve | |
The Graphics Interchange Format ('''GIF''') is an 8-bit-per-pixel Bitmap Image Format that was introduced by CompuServe in 1987 and has since come into widespread usage on the World Wide Web due to its wide support and portability. The format uses a palette of up to 256 distinct colors from the 24-bit RGB color space. It also supports animations and allows a separate palette of 256 colors for each frame. The color limitation makes the GIF format unsuitable for reproducing color photographs and other images with continuous color, but it is well-suited for more simple images such as graphics or logos with solid areas of color. GIF images are compressed using the Lempel-Ziv-Welch (LZW) Lossless Data Compression technique to reduce the file size without degrading the visual quality. This compression technique was patented in 1985. Though the relevant patents have all since expired, the controversy over the licensing agreement between the patent holder, Unisys , and CompuServe in 1994 led to the development of the Portable Network Graphics (PNG) standard. HISTORY CompuServe introduced the GIF format in 1987 to provide a color image format for their file downloading areas, replacing their earlier RLE format, which was black and white only. GIF became popular because it used LZW Data Compression , which was more efficient than the Run-length Encoding that formats such as PCX and MacPaint used, and fairly large images could therefore be downloaded in a reasonable amount of time, even with very slow Modem s. The original version of the GIF format was called ''87a''. In s of the file, which, when interpreted as ASCII , read "GIF87a" and "GIF89a", respectively. When the World Wide Web gained popularity, GIF became one of the two image formats commonly used on Web sites, the other being the black and white XBM . JPEG came later with the Mosaic Browser . The GIF89a feature of storing multiple images in one file, accompanied by control data, is used extensively on the web to produce simple Animations . The optional interlacing feature, which stored image scan lines out of order in such a fashion that even a partially downloaded image was somewhat recognizable, also helped GIF's popularity, as a user could abort the download if it was not what was required. PRONUNCIATION |
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