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jpg
source: www.webfront.net.au:
JPEG Is a lossy compressed format supporting 24-bit, over 16 million colors. Used mainly for full-color and grey scale naturalistic images. Use JPEG when the image has at least 16 colors. JPEG is not good for small, detailed text or images with hard edges. The JPEG standard is excellent for most realistic images (photos for example, but not line drawings or logos). It uses a powerful, though nominally "lossy", compression method. JPEG is best suited for truecolor original images; avoid using it on images that have already been forced into a 256-color palette(causes the picture to become extemely ugly!).
Using JPEG for a photographic image for example can produce 10:1 savings compared to GIF, as well as permitting much better display quality on truecolor-capable displays. The particular format usually used for JPEG-compressed images on the Web is JFIF. This is distinct from a JPEG compressed PICT file, which is often referred to as 'a JPEG file' on the Macintosh platform. A newer format called SPIFF is under development; when released, it is expected to be compatible with JFIF readers.
Although the "baseline" variety of JPEG is believed patent-free, there are many patents associated with some optional features of JPEG, namely arithmetic coding and hierarchical storage. For this reason, these optional features are never used on the Web.
Note: JPG is a "lossy" compression, resulting in data loss. Make sure you have your original somewhere and just make a copy to compress. Once you compress the data, the information is lost and you can't restore the image.
See also the JPEG FAQ.
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jpg
(Graphics) JPG
Acronym for "Joint Photographic Experts Group"source: www.webfront.net.au:
JPEG Is a lossy compressed format supporting 24-bit, over 16 million colors. Used mainly for full-color and grey scale naturalistic images. Use JPEG when the image has at least 16 colors. JPEG is not good for small, detailed text or images with hard edges. The JPEG standard is excellent for most realistic images (photos for example, but not line drawings or logos). It uses a powerful, though nominally "lossy", compression method. JPEG is best suited for truecolor original images; avoid using it on images that have already been forced into a 256-color palette(causes the picture to become extemely ugly!).
Using JPEG for a photographic image for example can produce 10:1 savings compared to GIF, as well as permitting much better display quality on truecolor-capable displays. The particular format usually used for JPEG-compressed images on the Web is JFIF. This is distinct from a JPEG compressed PICT file, which is often referred to as 'a JPEG file' on the Macintosh platform. A newer format called SPIFF is under development; when released, it is expected to be compatible with JFIF readers.
Although the "baseline" variety of JPEG is believed patent-free, there are many patents associated with some optional features of JPEG, namely arithmetic coding and hierarchical storage. For this reason, these optional features are never used on the Web.
Note: JPG is a "lossy" compression, resulting in data loss. Make sure you have your original somewhere and just make a copy to compress. Once you compress the data, the information is lost and you can't restore the image.
See also the JPEG FAQ.
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