(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.
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.
 | Reproduced with permission from Computer Desktop Encyclopedia. Copyright (c) 1981-2008 The Computer Language Company Inc. All rights reserved. |
Additional Resources
- iPhone update kills 12 security bugs
- Apple has released iPhone OS 2.2 with patches for 12 documented security flaws, some very serious. The vulnerabilities covered by the patch which also affect iPod Touch could allow remote code execution, information theft, software crashes and weakened encryption settings. The skinny on this...
- Blog posts 2008-11-21
- Apple fixes 12 Safari security flaws
- Apple has release Safari 3.2 to fix at least a dozen security flaws, some very serious. The update, available for Windows XP, Windows Vista and Mac OS X Tiger and Leopard, address vulnerabilities that could be exploited to take full control of a compromised machine. ...
- Blog posts 2008-11-13
- Apple ships patch for iLife security flaws
- Apple has shipped a major iLife security update to fix three documented vulnerabilities that could expose Mac OS X users to arbitrary code execution attacks. The flaws patched with the new iLife Support 8.3.1 could be exploited via specially crafted TIFF or JPEG images, Apple warned in...
- Blog posts 2008-11-10
- Apple mega-patch covers 34 Mac OS X security issues
- Apple has shipped another mega-update to address security vulnerabilities affecting Mac OS X users, warning that the most serious issues could lead to arbitrary code execution attacks. The update, available for Tiger and Leopard, addresses a total of 34 documented vulnerabilities, some in third-party components like ClamAV,...
- Blog posts 2008-09-15
- Tiff Counter (zip)
- Tiff Counter is an easy to use Tiff page count application. It supports all versions of single and multi-page tiff files. Tiff counter also support tiff files which is compressed with LZW compression. Tiff counter also the known to be fastest tiff counting application for windows. Ideal for imaging bureaus...
- Software downloads 2008-07-03
- PrintKey-Pro (exe)
- PrintKey-Pro is a system tray-based program that captures all or any part of the picture on your monitor screen with the press of the Print Screen key or any other available Hotkey combination that you configure. Adjust the captured picture's brightness, contrast, color balance, size, color invert, and convert to...
- Software downloads 2008-03-31
- Adobe Photoshop Update (jsp)
- The Adobe Photoshop 9.0.2 Update fixes a number of problems discovered after Photoshop 9.0 was released. Key new features include file browser performance enhancements; no more shifting of the color of white areas in CMYK files saved as JPEG files; correctly written TIFF files with LZW compression; and improved compatability...
- Software downloads 2007-10-22
- TIFF To PDF ActiveX Component (exe)
- Convert TIFF files to PDF Support single or multiple page TIFF Support various TIFF encoding such as CCITT G3/G4, LZW, RLE and uncompressed Merge multiple TIFF files into one PDF Standalone, doesn't depend on Adobe Acrobat or Reader Provide demos in ASP, VB, VB Script, and VB.Net. Version 2.0.2007.901 fixes...
- Software downloads 2007-10-19
- The real issue in the software patent fight
- The real issue in the software patent fightThis is why the issue NEEDS to come before the Supreme Court ...The legal basis of Software Patents has never been tested before the Supreme Court. The reason for that is that heretofore all of the litigants in Software Patent cases have...
- Discussion threads 2007-10-15
- x360soft - Image Processing ActiveX OCX (exe)
- X360 Tiff Image Processing ActiveX OCX help you to create and maintain multiple Tiff. You can append, delete, insert, move and swap pages within existing Tiff. You can also view and save images to different formats include BMP, GIF, JPEG, PDF, multipaged PDF, PNG, TIFF, multipaged TIFF, WMF. Major functions...
- Software downloads 2007-10-01
- Image Components (zip)
- Main Image Components functions are: opening file or directory and saving most common images file types (*.tif, *.jpg, *.bmp, *.gif, *.png) and convert between them. Thumbnail view of the image multi or single page. Navigation between the pages, by thumbnail click or by toolbar. Image fit to the screen (original,...
- Software downloads 2007-06-13
- Microsoft wins in second Alcatel-Lucent patent suit
- Microsoft wins in second Alcatel-Lucent patent suitMicrosoft wins in second Alcatel-Lucent patent suitGreat victory for Microsoft and everyone else that uses the mp3 format! This ruling plus the one that will be overturned in the appeals court means everyone can listen to mp3s safely. You all should be...
- Discussion threads 2007-03-02
- Software patents and the dependency problem
- Ive long taken a dim view of software patents. I wrote this piece as far back as 2003, arguing that Europe should avoid copying the American approach to software patents, both because they are unnecessary to spur innovation and because it would be useful for Europe to demonstrate why. There...
- Blog posts 2007-02-23
- CrackTiff (exe)
- CrackTiff is a tif tiff converter and merger, able to convert tif tiff files from one compression mode into another, such as convert uncompressed tif tiff files into PackBits, group 3, group 4, LZW or JPEG compressed tif tiff files. You can also combine merge multiple tif tiff files into...
- Software downloads 2007-01-19
- Patent reform needs to go further
- The US Supreme Court is currently hearing arguments in a case that could result in tighter rules for new patents. By dancing around the meaning of the word "obvious," the result, hopefully, is a ruling that makes it harder for patents that are truly obvious (even though some...
- Blog posts 2006-11-29
- TIFF To PDF Convert Command Line (zip)
- Supports virtually all TIFF compressions, including ZIP, LZW, CCITT G4/G3, JPEG, Packbits. Can combine multiple directories and tiff into one PDF file. Supports Multi-page tiff file to PDF conversion. Append to existing PDFs. Supports encryption with 40 or 128 bit. Can set automatic despeckling (of B/W images; removes noise) and...
- Software downloads 2006-09-05
- Tiff To PDF COM/SDK (zip)
- Supports virtually all TIFF compressions, including ZIP, LZW, CCITT G4/G3, JPEG, Packbits. Can combine multiple directories and tiff into one PDF file. Supports Multi-page tiff file to PDF conversion. Append to existing PDFs. Supports encryption with 40 or 128 bit. Can set automatic despeckling (of B/W images; removes noise) and...
- Software downloads 2006-09-05
- Tiff To PDF COM/SDK Unlimited License (zip)
- Supports virtually all TIFF compressions, including ZIP, LZW, CCITT G4/G3, JPEG, Packbits. Can combine multiple directories and tiff into one PDF file. Supports Multi-page tiff file to PDF conversion. Append to existing PDFs. Supports encryption with 40 or 128 bit. Can set automatic despeckling (of B/W images; removes noise) and...
- Software downloads 2006-09-05
- The benefit of the information commons - part 3
- Frank Capra's "It's a Wonderful Life" is a Christmas classic, at least in the United States. I love the movie, and though I've probably seen it at least 50 times, I still enjoy watching it. Oddly enough, the movie was not successful at the box office, and was largely forgotten...
- Blog posts 2006-01-19
- Is it time to boycott the JPEG graphics file format?
- Is it time to boycott the JPEG graphics file format?On TargetGreat points David.Personally I'll stick with PNG.As far as DRM goes, it's a deal breaker. I won't use anything which takes control away from me or restricts me. If that means I will have to do without some things then...
- Discussion threads 2005-10-28
Neighboring Terms
Premier Vendor Content Whitepapers, webcasts & resources from our Power Center Sponsors
- Do more. Sacrifice less
-
"Intel® Xeon® processor-based servers are optimized for virtualization and allow IT to load more virtual machines without sacrificing speed. They can also help you save time and money while delivering great performance, flexibility, and headroom for growth.
- See the benefits of hardware-based virtualization >>
CIO Sessions
- Check out our video interviews with leading CIOs today!
-
Differentiating Technorati from Google Technorati VP of Engineering: Dorion Carroll 11:50 -
On the Issues: From Net neutrality to bandwidth caps Qwest CTO: Pieter Poll 11:50 -
How to process over 300 million transactions per day Visa CIO: Michael Dreyer 11:30 -
Adopting collaboration tools in the enterprise Cisco CIO: Rebecca Jacoby 12:35 - All CIO Sessions »
