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File formats: some rough definitions File Formats: different ways of organising, storing and retrieving the electronic information that represents your documents, pictures etc. BMP a bit map (often spelled "bitmap") defines a display space and the color for each pixel or "bit" in the display space. A GIF and a JPEG are examples of graphic image file types that contain bit maps. GIF (the original and preferred pronunciation is DJIF; it stands for Graphics Interchange Format) is one of the two most common file formats for graphic images on the World Wide Web. The other is the JPEG. On the Web and elsewhere on the Internet (for example, bulletin board services), the GIF has become a de facto standard form of image. JPG (pronounced jay-peg, from "Joint Photographic Experts Group") is a picture format used on computers for photographic images or illustrations with complex shading and is the format of choice for this type of image on the internet (web pages, emails etc). It is recognised ("supported") by almost all browsers. When you save a picture in .jpg format a complex formula (algorithm) is applied which selects and discards varying amounts of "unnecessary" electronic information. This effectively compresses the picture file (by up to and in excess of 20:1) thus requiring considerably less storage space. When the file is "opened" again an approximation of the missing bits is provided by the algorithm and inserted in the "holes" in the picture, which returns to its original dimensions although with the loss of varying amounts of quality (hence: .jpg's are "lossy" files). Nevertheless, pictures using the .jpg format look realistic since all of the computer's 16+ million possible colours can be used to make up the picture. TIFF (pronounced tiff, from "Tagged Image File Format") is a common format for exchanging raster graphics (bitmap) images between application programs, including those used for scanner images. A TIFF file can be identified as a file with a ".tiff" or ".tif" file name suffix. One of the most common graphic image formats, TIFF files are commonly used in desktop publishing, faxing, 3-D applications, and medical imaging applications but are not supported by the major browsers and so are not for use in web pages or emails. "That's all I've got to say about file formats" Forrest Gump. |
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