LZW

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|pronom={{PRONOM|x-cmp/12}}
 
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|released=1984
 
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LZW (Lempel-Ziv-Welch) is a lossless compression algorithm based on [[LZ78]]. It was developed by Terry Welch in 1984. It is infamous for being widely used in various standard formats (especially [[GIF]]) by developers unaware that it was encumbered by [[patents]]. The patents expired around 2003.
  
[[LZW]] (Lempel-Ziv-Welch) is a widely used lossless compression algorithm used primarily for images.  It is the compression scheme used in [[GIF]] and is frequently used in [[TIFF]] images.  Developed by Terry Welch in 1984.  All patents on the LZW algorithm worldwide have expired.  
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There are many variations of LZW in use. In general, LZW compresses a stream of ''symbols'' into a stream of bits. For general-purpose file compression, the symbols are usually taken to be bytes, but for GIF format the symbols are pixels.
  
== References ==
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== Related formats ==
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* [[GIF]]
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* [[TIFF]]
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* [[compress]]
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== Resources ==
 
* [http://www.cs.duke.edu/courses/spring03/cps296.5/papers/welch_1984_technique_for.pdf A Technique for High-Performance Data Compression] Welch, Terry A.  Computer, Vol. 17, No. 6 (June 1984): pp. 8-19
 
* [http://www.cs.duke.edu/courses/spring03/cps296.5/papers/welch_1984_technique_for.pdf A Technique for High-Performance Data Compression] Welch, Terry A.  Computer, Vol. 17, No. 6 (June 1984): pp. 8-19
 
* [http://en.wikipedia.org/wiki/LZW Lempel-Ziv-Welch : Wikipedia]
 
* [http://en.wikipedia.org/wiki/LZW Lempel-Ziv-Welch : Wikipedia]

Revision as of 00:53, 2 May 2013

File Format
Name LZW
Ontology
PRONOM x-cmp/12
Released 1984

LZW (Lempel-Ziv-Welch) is a lossless compression algorithm based on LZ78. It was developed by Terry Welch in 1984. It is infamous for being widely used in various standard formats (especially GIF) by developers unaware that it was encumbered by patents. The patents expired around 2003.

There are many variations of LZW in use. In general, LZW compresses a stream of symbols into a stream of bits. For general-purpose file compression, the symbols are usually taken to be bytes, but for GIF format the symbols are pixels.

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