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	LZ77 and LZ78 - Wikipedia, the free encyclopedia
		LZ77 and LZ78 are the names for the two lossless data compression algorithms published in papers by Abraham Lempel and Jacob Ziv in 1977 and 1978.
		LZ77 is the "sliding window" compression algorithm, which was later shown to be equivalent to the explicit dictionary technique first given in LZ78.
		LZ77 algorithms achieve compression by replacing portions of the data with references to matching data that has already passed through both encoder and decoder.
	en.wikipedia.org /wiki/LZ77 (778 words)

	LZ77 (Site not responding. Last check: 2007-10-30)
		The LZ77 algorithm works by keeping a history window of the most recently seen data and comparing the current data being encoded with the data in the history window.
		As of 2002, the most popular LZ77 algorithm is called DEFLATE; it combines LZ77 with Huffman coding.
		LZ78 never became as popular as LZ77 because for the first few decades after it was introduced, LZ78 was somewhat of a patent minefield in the United States, while LZ77 is not patented.
	bopedia.com /en/wikipedia/l/lz/lz77.html (302 words)

	Understanding the Lempel-Ziv Data Compression Algorithm in Java
		LZ77 is the name commonly given to a lossless data compression algorithm published in papers by Abraham Lempel and Jacob Ziv in 1977.
		LZ77 is known as a dictionary encoding algorithm, as opposed for example to the Huffman encoding algorithm, which is a statistical encoding algorithm.
		The LZ77 algorithm is based on the use of two sliding contiguous windows on the data being compressed.
	www.developer.com /java/data/article.php/3586396 (9632 words)

	Class notes CS251B -- Winter 1997
		LZ77 and LZ78, two dictionary-based data compression techniques described by these two researchers, provided a whole new way of viewing the world of data compression.
		The highly innovative LZ77 and LZ78 methods, although usually referred to as the singular Lempel-Ziv (LZ) or Ziv-Lempel method, are in fact considerably different.
		In both cases, encoding proceeds "on the fly," so that as symbols are read in, more and more phrases are stored (in that respect, the LZ compression techniques are a bit like a suffix trie).
	cgm.cs.mcgill.ca /~hagha/topic23/topic23.html (1544 words)

	LZSS - Wikipedia, the free encyclopedia
		LZSS is a lossless data compression algorithm, a derivative of LZ77, that was created in 1982 by James Storer and Thomas Szymanski.
		Unlike Huffman coding, which attempts to reduce the average amount of bits required to represent a symbol, LZSS attempts to replace a string of symbols with a reference to a dictionary location of the same string.
		The main difference between LZ77 and LZSS is that in LZ77 the dictionary reference could actually be longer than the string it was replacing.
	en.wikipedia.org /wiki/LZSS (338 words)

	Method of compressing data with an alphabet - Patent 6262675
		An improved LZ77 data compression and decompression method, known as Le'Z99, uses an embedded alphabet to optimize code space and speed in the compressed data.
		The prior art LZ77 method solves this problem as follows: after each pointer, it outputs the first character in the lookahead buffer after the match; if there is no match, then it outputs a null-pointer and the character at the coding position.
		However, the Le'Z99 method encodes the input data 112, not based on the backward window W, but based on a coding window CW, which is a concatenation of the backward window W (which need not be a fixed size) and the alphabet window A (which generally is a fixed size).
	www.freepatentsonline.com /6262675.html (3297 words)

	[No title] (Site not responding. Last check: 2007-10-30)
		The compression ratio of LZ77 is improved by the remaining UDVM memory, which is used to store a history buffer containing the previously decompressed messages.
		LZW compression operates in a similar manner to LZ77 in that it maintains a circular buffer of previously received decompressed data, and each compressed character references exactly one byte string from the circular buffer.
		LZ77 0x0f86 0389 8d89 1588 8800 011c 0420 0d13 5051 2222 5051 16f5 2300 0x00bf c086 a08b 06 A.1.2.
	www.ietf.org /rfc/rfc4464.txt (5706 words)

	Hacking Data Compression - Lesson 7
		They are known as LZ77 and LZ78, referring to the papers published by Ziv and Lempel in 1977 and 1978, respectively (the transposition of 'L' and 'Z' was made early and propagated widely).
		Instead of encoding an index referring to a dictionary full of strings, it encodes a triple , where "off" is the file offset at which the string starts, "len" is the length of the match, and "char" is the first character that didn't match.
		This is just a simple string comparison, so a simple-minded approach would roll through and compare every string in turn (i.e., compare F bytes starting from offset 0 with the bytes in the lookahead buffer, then compare F bytes starting from offset 1, and so on).
	www.fadden.com /techmisc/hdc/lesson07.htm (3137 words)

	[No title] (Site not responding. Last check: 2007-10-30)
		LZ77 became the first of two compression algorithm presented by Lempel and Ziv.
		Basically a fixed-size "sliding window" is shifted across the data, while a pointer keeps track of where you are with respect to other data.
		Decompression is fast and easy: whenever a (P, L) value pair is encountered, go to that "position" in the window and copy "length" next bytes to the output.
	www.eecis.udel.edu /~staiano/ELEG867/lz77.html (242 words)

	LZSS (LZ77) Discussion and Implementation
		In the case of LZ77, the predecessor to LZSS, that wasn't always the case.
		The LZSS algorithm and it's predecessor LZ77 attempt to compress series of strings by converting the strings into a dictionary offset and string length.
		In their original LZ77 algorithm, Lempel and Ziv proposed that all strings be encoded as a length and offset, even strings with no match.
	michael.dipperstein.com /lzss (2834 words)

	LZW, BTEC, and slow compression
		And then, at some point, people realized that LZ77 was actually a more efficient method for many implementations: The length/offset matches + literals took up the same or less space than an LZ78 dictionary of the same material, and LZ77 had other benefits like much simpler decoding requirements (which directly translates to decompression speed).
		however, LZ77 can refer to any arbitrary string that had occured previously, wheras LZW is limited to whatever is in the dictionary.
		yeah, LZ77 is looking good, just I figured maybe I could squeeze more out of LZW, eg, by mapping the dictionary directly to the huffman tree so that in effect the bit-code refers directly to the string in question, vs a length/offset pair.
	www.codecomments.com /message418140.html (2620 words)

	Lossless Data Compression Program: Hybrid LZ77 RLE
		Pucrunch is a Hybrid LZ77 and RLE compressor, uses an Elias Gamma Code for lengths, mixture of Gamma Code and linear for LZ77 offset, and ranked RLE bytes indexed by the same Gamma Code.
		The distribution of the LZ77 offset values (pointer to a previous occurrance of a string) is not at all similar to the length distribution.
		Because LZ77 is the most frequently used primary unit, this presents a saving that more than compensates for the loss of 2-byte LZ77 matches with offsets 257..768 (which we can no longer represent, because we fixed the offset for 2-byte matches to use exactly 8 bits).
	www.cs.tut.fi /~albert/Dev/pucrunch (13324 words)

	LZ77 compression from FOLDOC (Site not responding. Last check: 2007-10-30)
		LZ77 compression keeps track of the last n bytes of data seen, and when a phrase is encountered that has already been seen, it outputs a pair of values corresponding to the position of the phrase in the previously-seen buffer of data, and the length of the phrase.
		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.
		An algorithm was developed which combines the ideas behind LZ77 and LZ78 to produce a hybrid called LZFG.
	foldoc.org /?LZ77 (303 words)

	LZ77 Compression (Site not responding. Last check: 2007-10-30)
		LZ77 compression is a precursor to LZW compression (An LZW-compressing virtual filesystem), I believe.
		Lars H: Mostly no; the precursor to LZW is LZ78, which apart from (i) being invented by the same Lempel and Ziv and (ii) belongs to same general group of compression algorithms (dictionary-based), is quite different from LZ77 -- for one, LZ78 (implicitly) constructs a dictionary of phrases.
		As gzip uses LZ77 (and Huffman encoding), I decided to start by implementing such an algorithm.
	wiki.tcl.tk /12368 (849 words)

	The LZ77 algorithm (Site not responding. Last check: 2007-10-30)
		Since it is possible that not even a one-character match can be found, the output cannot contain just pointers.
		LZ77 solves this problem this way: after each pointer it outputs the
		The first character in the input stream has the coding position 1.
	oldwww.rasip.fer.hr /research/compress/algorithms/fund/lz/lz77.html (351 words)

	A guide to PNG optimization
		In the second stage, the filtered byte sequence is passed through the Ziv-Lempel algorithm (LZ77), producing LZ77 codes that are further compressed by the Huffman algorithm in the third and final stage.
		The maximum size of the LZ77 sliding window in Deflate is 32768 bytes, and the LZ77 matches can be between 3 and 258 bytes long.
		The output of LZ77 is fed into a buffer which is occasionally flushed by sending a static Huffman tree followed by all the Huffman codes, to the output of Deflate.
	www.cs.toronto.edu /~cosmin/pngtech/optipng.html (3118 words)

	LZ77 Data Compression (Site not responding. Last check: 2007-10-30)
		Fiala and Greene obtained in 1990 a patent (4,906,991) on all implementations of LZ77 using a tree data structure.
		Phil Katz, author of pkzip, also has a patent on LZ77 (5,051,745) but the claims only apply to sorted hash tables, and when the hash table is substantially smaller than the window size.
		IBM patented (5,001,478) the idea of combining a history buffer (the LZ77 technique) and a lexicon (as in LZ78).
	home.earthlink.net /~neilbawd/pall.html (1265 words)

	DataCompression.info - LZ77/LZSS and derivatives (Site not responding. Last check: 2007-10-30)
		This topic encompasses the LZ77 algorithm and its descendant, LZSS.
		Christian Scheurer wrote up his LZ77 project that was targeted to the 68HC11 processor.
		This algorithm, later known as LZ77, is still one of the most widely used techniques for lossless data compression in use today.
	datacompression.info /LZSS.shtml (1939 words)

	Notes From The Comp.Compression FAQ
		Phil Katz, author of PKZIP, also has a patent on LZ77 (US Patent 5051745) but the claims only apply to sorted hash tables, and when the hash table is substantially smaller than the window size.
		IBM patented (US Patent 5001478) the idea of combining a history buffer (the LZ77 technique) and a lexicon (as in LZ78).
		Chambers US Patent 5155484 is yet another variation of LZ77 with hashing.
	www.ross.net /compression/patents_notes_from_ccfaq.html (1001 words)

	The Flate/deflate compression algorithm (Site not responding. Last check: 2007-10-30)
		The lossless deflate compression algorithm is based on two other compression algorithms: huffman encoding and LZ77 compression.
		Compression, first with LZ77 and then with a slightly modified version of Huffman coding.
		Compression, first with LZ77 and then with a slightly modified version of Huffman coding with trees that the compressor creates and stores along with the data.
	www.prepressure.com /techno/compressionflate.htm (285 words)

	Lz77 by Arturo San Emeterio Campos
		This scheme, lz77, is very used because it's easy to implement and also it's fast.
		The way I present you Lz77, will not lead you to do an archiver, but may be very interesting for internal data of your programs.
		And that's what we actually use, but lzss it's commonly called lz77, so we'll call it lz77 from this point at on, but remember that it can also be named Lzss.
	www.arturocampos.com /ac_lz77.html (4613 words)

	LZ77 (algorithm) - Biocrawler (Site not responding. Last check: 2007-10-30)
		New: Biocrawler.com now with the option to add inline videos.
		LZ78 never became as popular as LZ77, possibly because for the first few decades after it was introduced, parts of LZ78 were patent encumbered in the United States, while LZ77 is not patented.
		The most popular form of LZ78 compression was the LZW algorithm, a modification of the LZ78 algorithm made by Terry Welch.
	www.biocrawler.com /encyclopedia/LZ78 (448 words)

	Hacking Data Compression - Lesson 10
		Most of what you need to know was covered in the description of LZ77 back in lesson 7.
		Recall that the LZ77 dictionary is the last few thousand bytes of input (typically 4K or 8K).
		Recall from lesson 7 that LZ77 tries to match an input string against every position in the sliding window (usually implemented as a ring buffer).
	www.fadden.com /techmisc/hdc/lesson10.htm (4007 words)

	Compression Patents Sorted By Coverage
		US Patent 5016009 - LZ77 with offset hash table (extended in 5126739).
		US Patent 5126739 - LZ77 with offset hash table (extension of 5,016,009).
		US Patent 5155484 - LZ77 with 2-char 64K hash table.
	www.ross.net /compression/patents_by_coverage.html (339 words)

	Learn more about LZ77 in the online encyclopedia. (Site not responding. Last check: 2007-10-30)
		Learn more about LZ77 in the online encyclopedia.
		Enter a phrase or search word in the box below.
		Hint: Play with putting spaces before and after your words to see the different results you get.
	www.onlineencyclopedia.org /l/lz/lz77.html (379 words)

	[8] What about patents on data compression algorithms?
		(b) LZ77 - Waterworth patented (4,701,745) the algorithm now known as LZRW1, because Ross Williams reinvented it later and posted it on comp.compression on April 22, 1991.
		Claim 1 of the patent is much broader than the algorithms published by Fiala and Greene in Comm.ACM, April 89.
		If a string to be compressed is found in the symbol stream, a code is output designating the location within the search window of the matching string and the length of the matching string.
	www.faqs.org /faqs/compression-faq/part1/section-7.html (2861 words)

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