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| | LZW - Wikipedia, the free encyclopedia |
 | | LZW (Lempel-Ziv-Welch) is an implementation of a lossless data compression algorithm created by Lempel and Ziv. | | | It was published by Terry Welch in 1984 as an improved version of the LZ78 dictionary coding algorithm developed by Abraham Lempel and Jacob Ziv. | | | Others who like distinguishing between the algorithm and the code prefer calling the algorithm LZ and the code written by Welch as LZW. |
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http://en.wikipedia.org/wiki/LZW
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| | LZW Data Compression |
| | One reason for the efficiency of the LZW algorithm is that it does not need to pass the string table to the decompression code. | | | The code that the LZW algorithm outputs can be of any arbitrary length, but it must have more bits in it than a single character. | | | A quick examination of the algorithm shows that LZW is always trying to output codes for strings that are already known. |
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http://www.dogma.net/markn/articles/lzw/lzw.htm
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| | LZW compression - a Whatis.com definition |
| | LZW compression is the compression of a file into a smaller file using a table-based lookup algorithm invented by Abraham Lempel, Jacob Ziv, and Terry Welch. | | | A particular LZW compression algorithm takes each input sequence of bits of a given length (for example, 12 bits) and creates an entry in a table (sometimes called a "dictionary" or "codebook") for that particular bit pattern, consisting of the pattern itself and a shorter code. | | | The decoding program that uncompresses the file is able to build the table itself by using the algorithm as it processes the encoded input. |
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http://whatis.techtarget.com/definition/0,,sid9_gci214337,00.html
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| | Allegro: How to download/upload an LZW package file |
| | LZW packages files can be uploaded to an HP3000 as either fixed-record binary or variable-record binary files, unless you have an old version of the LZW program. | | | The upload of "LZW" package files must be in binary. | | | Once you have the file downloaded to the computer your browser is running on, you need to upload it to the HP3000. |
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http://www.allegro.com/software/hp3000/download_lzw.html
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| | LZW Data Compression |
| | This means that instead of tabulating character counts and building trees (as for Huffman encoding), LZW encodes data by referencing a dictionary. | | | If you were to take a look at almost any data file on a computer, character by character, you would notice that there are many recurring patterns. | | | Usually a maximum number of entries (say, 4096) is defined for the dictionary, so that the process doesn't run away with memory. |
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http://www.cs.duke.edu/csed/curious/compression/lzw.html
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| | LZW Compression |
| | LZW is a hashing algorithm, it is based on the idea of a dynamic vocabulary, shorthand for frequently repeated patterns. | | | When you have completed this process be sure to save BOTH the output codes and the alphabet section of the LZW table (another option would be to just initialize the alphabet with all 256-characters before compression, so that you don't have to save a dynamic one to the file). | | | Now keep in mind by the alphabet I don't mean the entire search table, I just mean the section that had 'abcd' (for the previous example). |
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http://www.geocities.com/ResearchTriangle/System/5245/programming/lzw.htm
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| | The GIF Controversy: A Software Developer's Perspective (lzw.info) |
| | LZW itself is a refinement of other algorithms published in the years before (Ziv-Lempel and others). | | | Normally, procedures such as LZW are published in magazines so that they can be shared by the community of software developers. | | | Only the software employing the LZW algorithm for writing GIF files is "at risk". |
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http://cloanto.com/users/mcb/19950127giflzw.html
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| | LZW coding algorithm |
| | LZW is a so-called commercial version of LZ78. | | | As it can be seen from the demonstrated examples of compression using LZ78 and LZW, these algorithms achieve maximal efficiency when the length of the input string is of infinitely long size. | | | The LZW algorithm uses the same principles and ideas as LZ78 does, while adding several technical improvements over LZ78. |
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http://www.cs.technion.ac.il/Labs/Isl/Project/Projects_done/VisionClasses/DIP/Lossless_Compression/node18.html
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| | Lempel-Ziv-Welch (LZW) Encoding Discussion and Implementation |
| | However, the LZW algorithm does not impose a limit on the length of strings that are encoded. | | | Entries in the LZW dictionary are strings, and every LZW code word is a reference to a string in the dictionary. | | | There are a few more issues to consider when actually implementing the algorithm on a computer. |
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http://michael.dipperstein.com/lzw
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| | [70] Introduction to data compression (long) |
| | LZW is more commonly encountered today in a variant known as LZC, after its use in the UNIX "compress" program. | | | LZW decompression takes the stream of codes and uses it to exactly recreate the original input data. | | | In effect the compressor moves a fixed-size *window* over the data (generally referred to as a *sliding window*), with the position part of the (position, length) pair referring to the position of the phrase within the window. |
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http://www.faqs.org/faqs/compression-faq/part2/section-1.html
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| | LZW hint |
| | LZW was chosen as the compression algorithm for the CompuServe GIF image format, as well as the TIFF image format. | | | Since free software is free, this became a problem for the free software industry. | | | This algorithm was used in a variety of software products, such as the UNIX compress command. |
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http://www.linuxfromscratch.org/pipermail/hints/2003-July/001642.html
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| | [No title] |
| | The LZW case illustrates one of the biggest problems with software patents--the very nature of software and algorithms leads programmers and scientists to freely adopt and exchange ideas that have been published in academic and non-academic literature. | | | Because the LZW algorithm had been so widely described in printed articles and other references, the programmers at CompuServe assumed that the algorithm was in the public domain. | | | (By no means is LZW specific to GIF files; the algorithm is also used in the TIFF image format, as well as a number of compression programs and hardware devices. |
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http://cse.stanford.edu/class/cs201/projects-99-00/software-patents/lzw.html
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| | LZW and LZ78 - Dev Shed |
| | LZW and LZ78 Software design forum discussing design principles and non-language specific algorithms. | | | It seems that the main difference is that LZW has a predefined table, but LZ78 encodes the table into the data stream. | | | Discuss LZW and LZ78 in the Software Design forum on Dev Shed. |
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http://forums.devshed.com/software-design-43/lzw-and-lz78t-80382.html
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| | Compression Links: LZ78/LZW and derivatives area |
| | The definition of LZW from the Free On-line Dictionary of Computing. | | | The definition of LZ78 from the Free On-line Dictionary of Computing. | | | It is the compression algorithm used in the GIF graphics file format, which is one of the standard graphic formats used by CompuServe and the World Wide Web. |
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http://www.compression-links.info/LZW
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| | Example compress algorithm, - LZW algorithm |
| | GIF example there is placed the practical adaptation of the algorithm LZW used in GIF files. | | | Attention: the algorithm LZW is protected by the patent. | | | The successive set elements flowing in serially beginning from the first element are the input raw material for the algorithm LZW. |
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http://www.semmix.pl/color/elempic/eep80.htm
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| | [No title] |
| | LZW manipulates three objects in both compression and decompression: the charstream, the codestream, and the string table. | | | COMPRESSION The LZW algorithm converts a series of data values into a series of codes which may be raw values or a code designating a series of values. | | | LZW - A sophisticated data compression algorithm based on work done by Lempel-Ziv & Welch which has the feature of very efficient one-pass encoding and decoding. |
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http://www.qzx.com/pc-gpe/gif.txt
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| | Interactive LZW Compression |
| | These algorithms were named LZ77 and LZ78, respectively. | | | Many files, especially text files, have certain strings that repeat very often, for example " the ". | | | To help demonstrate exactly what happens in the LZW algorithm, I wrote an Interactive LZW Compressor/Decompressor. |
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http://www.cs.sfu.ca/cs/CC/365/li/squeeze/LZW.html
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| | SCOTT STYLE BIJECTIVE LZW COMPRESSORs |
| | This is a bijective LZW with only 2 Roots 0 and 1 so its slow since each occurence of a binary string causes two new strings to occur in the table. | | | There is more than one way to make a LZW bijective this was the way I chose to do it However I will have others that use a different method. | | | The first Basic Binary Two Root Bijective LZW file and/or string compressor called LZW1 |
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http://bijective.dogma.net/compreslzw1.htm
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| | NewsForge Bringing back LZW compression |
| | Consequently, LZW compression support was rapidly and ruthlessly cut from virtually all free software. | | | There was some debate last year over whether IBM also held a patent on the LZW algorithm, but it has been settled -- IBM's patented compression is a cousin to LZW, but different. | | | In doing so, they could then distribute the 3.5.5 edition of the library with an empty "stub" file where the LZW routine would have resided. |
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http://software.newsforge.com/software/05/06/23/2150233.shtml?tid=130
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| | Sad day... GIF patent dead at 20 |
| | League for Programming Freedom believe that it should be impossible to patent algorithms, the fact remains that the LZW algorithm was implemented in disk controller hardware. | | | Adobe pay to license LZW in their Postscript language, but not for their GIF saver in Photoshop. | | | Like many IEEE Computer readers, Spencer decided to implement the LZW algorithm he read in the magazine, completely unaware that there was a patent pending on the technique. |
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http://www.kyz.uklinux.net/giflzw.php
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| | LZW Download |
| | LZW is a utility developed by Telamon Inc. that archives and compresses HP 3000 files. | | | This will create LZW as a program file that you can run on the HP 3000. | | | These files have been compressed into a single file using LZW, so you need LZW on your system to decompress them. |
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http://www.robelle.com/products/smartdate/lzw.html
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| | Dp: Lzw, gif decoding |
| | May be you could use the fpu, or the Mmx, or copying at least 4 bytes at a time. | | | At the start it's filled with the possible bytes (if 8 bits image, 0-255) then it starts to fill the dictionary, every time it gets the last used Codeword, appends to it the first byte of the current codeword, and then it puts it in the dictionary. | | | First it was made for implementation in hardware for high performance disk controllers and then Compuserve used it in the famous Gif, Graphics Interchange Format. |
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http://www.arturocampos.com/ac_lzw_gif.html
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| | Digital Light & Color Message Boards: LZW compression for TIFFs? |
| | LZW compression of tiff files has been on our wish list and may be added in a future upgrade. | | | There are also special compressoin algorithms designed to handle binary data, LZW was designed more for text where there is lots of repetition. | | | Peter, thankyou for the diligence of your test in respect of file size results with LZW and ZIP TIFF...most interesting food for thought, to see that a "compression" methodology can actually increase a file size.I haven't come across this in any references to LZW TIFF previously. |
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http://www.dl-c.com/cgi-bin/discus/show.cgi?2/5676
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| | LZW compression: conjugations patented |
| | Due to the LZW patent, the development of user interfaces that run within a web browser has come to a halt. | | | However, their answer to the second question was less precise: We do not agree or disagree with your statement regarding the relationship between an algorithm and a theorem. | | | gzip was developed as a replacement for compress because of the UNISYS and IBM patents covering the LZW algorithm used by compress. |
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http://swpat.ffii.org/patents/effects/gif-lzw/index.en.html
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| | Application Note about LZW Compression |
| | But for some images LZW can create a larger file than the original uncompressed image requires. | | | The Victor Library includes complete support for LZW compression and decompression within the GIF and TIFF-LZW image file formats. | | | The Victor Library includes complete support for optional LZW compression and decompression within the GIF and TIFF image file formats. |
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http://www.catenary.com/appnotes/lzwcomp.html
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| | Lzw - NewsForge Bringing back LZW compression |
| | Fast LZW implementation using Binary Tree as a dictionary. | | | The algorithm for LZW compression is as follows: set w = NIL loop read a [A good introduction to LZW, MW, AP and Y coding is given in the yabba package. | | | Definition of: LZW (Lempel-Ziv-Welch) A data compression method that stems from techniques LZW has been used in many hardware and software products, |
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http://findoutpages.com/?q=lzw
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| | AspImage, LZW and the Unisys Patent on GIF/LZW |
| | RLE is not patented by Unisys as the LZW algorithm is. Therefore we are free to provide copies of AspImage which use RLE encoding. | | | Unisys was locking us out of LZW support without any options. | | | Inclusion of GIFs in programs that read them Illegal according to Unisys! |
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http://www.serverobjects.com/lzw.html
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| | Unisys Web Site LZW Licenses Available |
| | Many Web site operators use commercially available software which creates GIF images offline which are then posted on their Web sites. | | | Because demand for LZW-related technology by Web developers continues to grow, Unisys wants to make obtaining a license for Web-based use of the LZW technology as easy and as straightforward as possible. | | | We have received numerous telephone calls and e-mails over the past few days asking about our recently posted information on the use of LZW technology on Web sites. |
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http://www.unisys.com/about__unisys/lzw/lzw__license__english.htm
(629 words)
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| | LZW Compression Encoding |
| | LZW is based on a translation table that maps strings of input characters into codes. | | | A lossless compression algorithm for digital data of many kinds, named for the creators Abraham Lempel and Jacob Ziv, and a later contributor, Terry Welch. | | | Relatively transparent but depends upon algorithms and tools to read. |
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http://www.digitalpreservation.gov/formats/fdd/fdd000135.shtml
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| | Allegro: LZW format |
| | If you agree, you'll be taken to a page where you choose which form of LZW you want (raw file or WRQ "label" format), and for which machine/operating system (e.g., MPE/iX, MPE V, MS DOS, HP-UX, AIX, Linux and many others). | | | It provides a convenient method of packaging MPE files, and retaining their file characteristics. | | | The program comes in something like two thousand versions, all of which have the same version number! |
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http://www.allegro.com/software/hp3000/lzw.html
(419 words)
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| | LZW definition of LZW in computing dictionary - by the Free Online Dictionary, Thesaurus and Encyclopedia. |
| | LZW has been used in many hardware and software products, including V.42bis modems, GIF, TIF and PDF files and PostScript Level 2. | | | LZW definition of LZW in computing dictionary - by the Free Online Dictionary, Thesaurus and Encyclopedia. | | | This information should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional. |
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http://computing-dictionary.thefreedictionary.com/LZW
(182 words)
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| | INFO: Unisys GIF and LZW Technology License Information |
| | Microsoft has obtained a license from Unisys to use the.gif file format and other LZW technologies covered by the Unisys-owned U.S. and foreign patents in a number of Microsoft products. | | | This article provides information about licensing issues regarding the.gif file format and the Lempel Ziv Welch (LZW) data compression and decompression technology. | | | However, this license does not extend to third-party developers using Microsoft development products to develop applications. |
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http://support.microsoft.com/default.aspx?scid=kb;en-us;Q193543
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| | License Information on GIF and Other LZW-based Technologies |
| | Unisys therefore cautions recipients, users and distributors of hardware or software products containing LZW conversion capability to make sure that they are lawfully acquiring and/or distributing licensed LZW software. | | | Microsoft's license does NOT extend to software developers or third parties who use Microsoft toolkit, language, development or operating system products to provide GIF read/write and/or any other LZW capabilities in their own products (e.g., by way of DLLs and APIs). | | | The complete statement by Microsoft can be found at Microsoft's developer-oriented Web site at |
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http://burnallgifs.org/archives/lzw-main.html
(653 words)
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| | LZW - OneLook Dictionary Search |
| | LZW : Dictionary of Computing and Digital Media [home, info] | | | .lzw : Data Formats and Their Sugggested File Extensions [home, info] | | | Phrases that include LZW: lzw compression, lzw compression algorithm |
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http://www.onelook.com/cgi-bin/cgiwrap/bware/dofind.cgi?word=LZW
(140 words)
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| | LZW Compression/Decompression Method |
| | The below are the demo program which is written based on LZW method. | | | Consider the below uncompressed string and its predefined dictionary. | | | Consider the below code and its predefined dictionary. |
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http://www.geocities.com/yccheok/lzw/lzw.html
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| | Re: lzw patent search (fwd) |
| | I would like to know when the last basic LZW patent expires and what agreements for the international distribution of the LZW algorithm might be available. | | | What Unisys patents/pending patents might cover the version of LZW that is used in the GIF file format, and/or Unix Compress? | | | > I also am unsure as to how to search for information about each of the lzw > patents. |
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http://lists.debian.org/debian-legal/2003/debian-legal-200303/msg00526.html
(335 words)
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| | Digital Light & Color Message Boards: TIFF & LZW compression |
| | There are no immediate plans to implement LZW TIFF saving. | | | I already use IrfanView but if I am working in PWP I also want to save LZW TIFF files. | | | Jonathan, please consider implementing LZW TIFF saving as I want to work with 48-bit TIFF images and would like to keep the size down without the lossy compression of JPEG. |
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http://www.dl-c.com/cgi-bin/discus/show.cgi?tpc=2&post=7262
(581 words)
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| | Re: TIFF and LZW -- Envision Support Forum |
| | Unfortunately, I cannot distribute any LZW code with Envision to avoid any legal problems. | | | > >Hi Tommy, > >Unfortunately, I cannot distribute any LZW code with >Envision to avoid any legal problems. | | | I you want to recompile some C sources I can give you some help. |
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http://www.voy.com/5188/1223.html
(334 words)
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| | Lempel-Ziv-Welch (LZW) Algorithm |
| | Implementation Note: LZW can be made really fast; it grabs a fixed number of bits from input stream, so bit parsing is very easy. | | | A 19-symbol input has been reduced to 7-symbol plus 5-code output. | | | The LZW algorithm is a very common compression technique. |
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http://www.cs.cf.ac.uk/Dave/Multimedia/node214.html
(298 words)
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| | LZW compression |
| | Gopinath Srinivasan, "LZW compression", from Dictionary of Algorithms and Data Structures, Paul E. Black, ed., NIST. | | | HTML page formatted Wed Oct 26 09:47:46 2005. |
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http://www.nist.gov/dads/HTML/LZWCompression.html
(50 words)
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| | LZW FAQ |
| | GIF has been outstanding for handling graphics files and its use of LZW technology is one of the factors in its success. | | | Keep in mind that Unisys can only license the patented LZW technology. | | | In fact, we have completed licensing agreements for LZW technology with over 100 companies since 1990, for products including hardware, software and on-line information services. |
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http://www-dse.doc.ic.ac.uk/~nd/surprise_95/journal/vol2/hml/article2.imag4.html
(1118 words)
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| | LZW compression patent expires |
| | Using a patented compression algorithm in a widely available data format (with an aggressive patent holder, Unisys) has been an issue for commercial software that manipulates GIF images for more than a decade now. | | | Abraham Lempel and Jacob Ziv first published their approach to data compression in 1977. | | | LZW compression is used in the GIF image format. |
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http://www.bobcongdon.net/blog/2004/06/lzw-compression-patent-expires.html
(188 words)
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| | LZW ( .LZW ) - File Extension Information |
| | LZW is the file extension for the Compressed Amiga archive associated with LHWARP. | | | To Backup LZW Files - Get WinBackup Now! | | | WinBackup 2.0 Standard is truly backup made easy! |
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http://www.liutilities.com/products/winbackup/filextlibrary/files/LZW
(255 words)
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| | [No title] |
| | Imaging-Components.com is an informational website created to promote the use of LEADTOOLS "third-party" imaging software components. | | | LZW compression is always used in GIF image files, and offered as an option in TIFF. | | | LZW compression is named after its developers, Lempel and Ziv, with later modifications by Welch. |
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http://www.leadtools.com/SDK/pocketpc/Raster-Compression-LZW.htm
(182 words)
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| | The different between Lzw and lz78 - Dev Shed |
| | When a phrase reoccurrs, it replaces it with an index number of the phrase in the dictionary. | | | This is a variation of the LZW method. | | | Viewing: Dev Shed Forums > Programming Languages > C Programming > The different between Lzw and lz78 |
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http://forums.devshed.com/c-programming-42/the-different-between-lzw-and-lz78t-80380.html
(242 words)
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| | GIF & LZW Not Supported in IDL 5.4 |
| | There are several Web sites that offer utilities for converting your images from the GIF file format to formats like PNG or JPG which IDL does support. | | | If you set the COMPRESSION keyword to a value of 1 (previously this created a TIFF file using LZW compression), the resulting TIFF file will be created using the "PackBits" compression algorithm. | | | If you set the COMPRESSION keyword to WRITE_TIFF to a value of 1 (previously this created a TIFF file using LZW compression), the resulting TIFF file will be created using the "PackBits" compression algorithm. |
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http://www.rsinc.com/services/techtip.asp?ttid=3036
(555 words)
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| | LZW - Lempel-Ziv-Welch |
| | More information about the definition of LZW may appear below: | | | Lempel-Zev-Welch are inventors of a compression scheme used by graphic files in the GIF format | | | Using LZW compression, you don't lose any data. |
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http://www.auditmypc.com/acronym/LZW.asp
(421 words)
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| | LZW and software patents - PowerBASIC Forums |
| | I sent them an email asking if I could write (and distribute) a program that dispays GIF files and they said that I'd need to pay a royalty. | | | The issue of software patents is controversial to say the least, but the patent on LZW exists. | | | A few years ago I investigated the issue of software patents as they apply to compression. |
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http://www.powerbasic.com/support/forums/Forum6/HTML/000280.html
(2703 words)
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| | [No title] |
| | _ µ ó ¨ Di-Gram LZW Implementation ¡ ª ¨¯ Output symbol has to be large enough to hold 1048576 values i.e. |
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http://ouray.cudenver.edu/~rk0kanas/Presentation.ppt
(830 words)
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| | Xpdf: LZW |
| | As of version 2.00, Xpdf includes a "native" LZW decoder. |
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http://www.foolabs.com/xpdf/lzw.html
(23 words)
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