Lempel–Ziv–Welch
universal lossless data compression algorithm
Lempel–Ziv–Welch (LZW) is a universal lossless compression algorithm created by Abraham Lempel, Jacob Ziv, and Terry Welch. It was published by Welch in 1984 as an improvement to the LZ78 algorithm published by Lempel and Ziv in 1978. Claimed advantages include: simple to implement and the potential for high throughput in a hardware implementation.
A large English text file can typically be compressed via LZW to about half its original size.
The algorithm became the first widely used universal data compression method used on computers. The algorithm was used in the compress program commonly included in Unix systems starting around 1986. It has since disappeared from many distributions, because it both infringed the LZW patent and because gzip produced better compression ratios using the LZ77-based DEFLATE algorithm. The algorithm found wide use when it became part of the GIF image format in 1987. It may optionally be used in TIFF and PDF files. Although LZW is available in Adobe Acrobat software, Acrobat by default uses DEFLATE for most text and color-table-based image data in PDF files.
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This entry incorporates text from “Lempel–Ziv–Welch” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.