Lempel-Ziv-Welch, or LZW, is a universal lossless data compression algorithm created by Abraham Lempel, Jacob Ziv and Terry Welch, with Welch publishing the algorithm in 1984 as an improvement on the 1978 LZ78 algorithm by Lempel and Ziv. It became the first widely used universal data compression method on computers and rose to particular prominence when it was built into the GIF image format in 1987; it remains available as an option in the TIFF and PDF file formats. On typical English text LZW can compress a file to roughly half its original size, though algorithms such as DEFLATE have since overtaken it in most applications by offering better compression ratios.
Facts
Patent or First-Use DateFiling date derived from the source's own statement that the US patent expired 20 years after filing, on June 20, 2003. SignificanceLZW became the first widely used universal data compression method on computers, and was later adopted into the GIF image format and used optionally in TIFF and PDF files. 1 Lempel-Ziv-Welch
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FAQs
When did the patent on the LZW algorithm expire?
The United States patent on LZW expired on June 20, 2003.
Unisys held a United States patent on the LZW algorithm. The patent expired on June 20, 2003, twenty years after it had been filed in 1983.
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Source Lempel-Ziv-Welch (Wikipedia)
Invented By
Source Lempel-Ziv-Welch (Wikipedia)
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1. Lempel-Ziv-Welch (Wikipedia)
Wikipedia contributors, Wikimedia FoundationLead section, first sentence
It was published by Welch in 1984 as an improvement to the LZ78 algorithm published by Lempel and Ziv in 1978.
Lead section, third paragraph
The algorithm became the first widely used universal data compression method used on computers.
Patents section
Unisys's US patent on the LZW algorithm expired on June 20, 2003, 20 years after it had been filed.
View the Source Lempel-Ziv-Welch (Wikipedia)
Associated With: Jacob Ziv, Article body
Lempel-Ziv-Welch (LZW) is a universal lossless compression algorithm created by Abraham Lempel, Jacob Ziv, and Terry Welch.
Invented By: Jacob Ziv, Article body
Lempel-Ziv-Welch (LZW) is a universal lossless compression algorithm created by Abraham Lempel, Jacob Ziv, and Terry Welch.
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