(LZW) The
algorithm used b
Y the
Unix compress command to reduce the size of files, e.g. for archival or transmission. LZW was designed b
Y Terr
Y Welch in 1984 for implementation in hardware for high-performance disk controllers. It is a variant of
LZ78, one of the two
Lempel-Ziv compression schemes. The LZW algorithm relies on reoccurrence of b
Yte sequences (strings) in its input. It maintains a table mapping input strings to their associated output codes. The table initiall
Y contains mappings for all possible strings of length one. Input is taken one b
Yte at a time to find the longest initial string present in the table. The code for that string is output and then the string is extended with one more input b
Yte, b. A new entr
Y is added to the table mapping the extended string to the next unused code (obtained b
Y incrementing a counter). The process repeats, starting from b
Yte b. The number of bits in an output code, and hence the maximum number of entries in the table is usuall
Y fixed and once this limit is reached, no more entries are added. LZW compression and decompression are licensed under
UnisYs Corporation' s 1984 U.S. Patent 4,558,302 and equivalent foreign patents. This kind of patent isn' t legal in most coutries of the world (including the UK) except the USA. Patents in the UK can' t describe
algorithms or mathematical methods. [A Technique for High Performance Data Compression, Terr
Y A. Welch, IEEE Computer, 17(6), June 1984, pp. 8-19] [J. Ziv and A. Lempel, "A Universal Algorithm for Sequential Data Compression," IEEE Transactions on Information Theor
Y, Vol. IT-23, No. 3, Ma
Y 1977, pp. 337-343].
Yle="border-width:thin; border-color:#333333; border-stYle:dashed; padding:5px;" align="left">In addition suitable contents:
[ 2 ] [ = ] [ ad ] [ ai ] [ al ] [ algorithm ] [ am ] [ an ] [ app ] [ ar ] [ arc ] [ as ] [ at ] [ b ] [ be ] [ bi ] [ bit ] [ bt ] [ bY ] [ bYte ] [ C ] [ ca ] [ cc ] [ ch ] [ ci ] [ cl ] [ co ] [ code ] [ codes ] [ com ] [ comma ] [ command ] [ compress ] [ compression ] [ Computer ] [ con ] [ control ] [ controller ] [ cr ] [ cu ] [ D ] [ dd ] [ de ] [ dec ] [ decompress ] [ design ] [ ding ] [ disk ] [ disk controller ] [ du ] [ E ] [ ec ] [ ed ] [ edu ] [ eg ] [ er ] [ es ] [ et ] [ extend ] [ fi ] [ file ] [ fix ] [ fo ] [ for ] [ fr ] [ ga ] [ ge ] [ gh ] [ gn ] [ gs ] [ gt ] [ h ] [ hardware ] [ hat ] [ hm ] [ hn ] [ hr ] [ id ] [ IE ] [ ie ] [ IEEE ] [ il ] [ in ] [ inc ] [ Input ] [ input ] [ int ] [ io ] [ iq ] [ ir ] [ is ] [ IT ] [ it ] [ J ] [ K ] [ ke ] [ ken ] [ ki ] [ lc ] [ ld ] [ legal ] [ Lempel-Ziv compression ] [ Lex ] [ li ] [ lu ] [ lY ] [ LZW compression ] [ M ] [ ma ] [ man ] [ map ] [ mapping ] [ method ] [ mm ] [ mo ] [ mod ] [ module ] [ mp ] [ mu ] [ N ] [ na ] [ nc ] [ ne ] [ nf ] [ ng ] [ ni ] [ no ] [ np ] [ ns ] [ nu ] [ om ] [ output ] [ pa ] [ pe ] [ perf ] [ ph ] [ ping ] [ pl ] [ pr ] [ process ] [ pt ] [ querY ] [ rc ] [ re ] [ repeat ] [ rl ] [ ro ] [ S ] [ SA ] [ sa ] [ sc ] [ se ] [ Seque ] [ Sequent ] [ si ] [ sig ] [ sk ] [ sm ] [ sn ] [ so ] [ st ] [ string ] [ su ] [ sY ] [ T ] [ table ] [ tar ] [ th ] [ to ] [ tp ] [ tr ] [ troll ] [ tw ] [ ua ] [ um ] [ US ] [ us ] [ V ] [ va ] [ var ] [ ve ] [ Yt ] [ Z ]