(LZW) The
algorithm used by the
Unix compress command to reduce the size of files, e.g. for archival or transmission. LZW was designed by Terry Welch in 1984 for implement
ATion 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 byte sequences (strings) in its input. It maintains a table mapping input strings to their associ
ATed output codes. The table initially contains mappings for all possible strings of length one. Input is taken one byte
AT a time to find the longest initial string present in the table. The code for th
AT string is output and then the string is extended with one more input byte, b. A new entry is added to the table mapping the extended string to the next unused code (obtained by incrementing a counter). The process repe
ATs, starting from byte b. The number of bits in an output code, and hence the maximum number of entries in the table is usually fixed and once this limit is reached, no more entries are added. LZW compression and decompression are licensed under
Unisys Corpor
ATion' s 1984 U.S. P
ATent 4,558,302 and equivalent foreign p
ATents. This kind of p
ATent isn' t legal in most coutries of the world (including the UK) except the USA. P
ATents in the UK can' t describe
algorithms or m
AThem
ATical methods. [A Technique for High Performance D
ATa Compression, Terry A. Welch, IEEE Computer, 17(6), June 1984, pp. 8-19] [J. Ziv and A. Lempel, "A Universal Algorithm for Sequential D
ATa Compression," IEEE Transactions on Inform
ATion Theory, Vol. IT-23, No. 3, May 1977, pp. 337-343].
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 ]