(Lempel-Ziv-Welch) A data compression method that stems from techniques introduced by Jacob Ziv and Abraham Lempel. LZW has been used in many hardware and software products, including V.42bis modems, GIF, TIF and PDF files and PostScript Level 2. The LZ77 method creates pointers back to repeating data, while LZ78 creates a dictionary of repeating phrases with pointers to those phrases.The Welch in Lempel-Ziv-Welch is for Terry Welch, the Unisys researcher who created an enhanced version of these methods that was patented by Unisys. Unisys collected royalties from thousands of software publishers whose applications used this algorithm until the patents expired in 2004. This was the most widely licensed data compression patent in history. See PNG.
A lossless data compression algorithm used in the Graphics Interchange Format (GIF) and optionally used in Tagged Image File Format (TIFF) files. LZW is named after its inventors, Abraham Lempel, Jacob Ziv, and Terry Welch. See also analog, channel, compression, DTE, GIF, link, lossless compression, modem, TIFF, LZ, and LZW.
Stands for Lempel-Ziv-Welch (Algorithm). The authors, Abraham Lempel and Jacob Ziv, presented the algorithm in 1977 as a lossless universal algorithm for sequential data compression. In 1984, Terry Welch improved the algorithm to its present form.