LZW Algorithm

Lempel-Ziv-Welch, or LZW, is a universal lossless compression algorithm created by Abraham Lempel, Jacob Ziv, and Terry Welch, published by Welch in 1984 as an improvement on the LZ78 algorithm Lempel and Ziv had published in 1978. It is simple to implement and offers the potential for high throughput in a hardware implementation, and a large English text file can typically be compressed to about half its original size. LZW became the first widely used universal data compression method on computers, used in the Unix compress program from around 1986, though it has since largely disappeared from distributions because it infringed the LZW patent and because gzip's LZ77-based DEFLATE algorithm produced better compression ratios. The algorithm found wide use when it became part of the GIF image format in 1987, and it may optionally be used in TIFF and PDF files, though Adobe Acrobat by default uses DEFLATE for most text and color-table-based image data in PDF files.