Welcome to the zlib Home Page, maintained by Greg Roelofs (on disk space provided by Walnut Creek CD-ROM). If this page seems suspiciously similar to the PNG Home Page, rest assured that the similarity is completely coincidental. No, really.
![[DDJ's zlib image]](images/zlib_ddj.gif)
zlib is designed to be a free, general-purpose, legally unencumbered --
that is, not covered by any patents -- lossless data-compression library for
use on virtually any computer hardware and operating system. The zlib data
format is itself portable across platforms. Unlike the LZW compression method
used in Unix compress(1), the compression method currently used in zlib
essentially never expands the data. (LZW can double or triple the file size in
extreme cases.) zlib's memory footprint is also independent of the input data
and can be reduced, if necessary, at some cost in compression. A more precise,
technical discussion of both points is available on another page.
zlib was written by Jean-loup Gailly (compression) and Mark Adler (decompression). Jean-loup is also the primary author/maintainer of gzip(1), the author of the comp.compression FAQ list and the former maintainer of Info-ZIP's Zip; Mark is also the author of gzip's and UnZip's main decompression routines and was the original author of Zip. Not surprisingly, the compression algorithm used in zlib is essentially the same as that in gzip and Zip, namely, the `deflate' method that originated in PKWARE's PKZIP 2.x.
Mark and Jean-loup can be reached by e-mail at zlib@quest.jpl.nasa.gov .
Greg, Mark and/or Jean-loup will add some more stuff here when they think of something to add. For now this page is mainly a pointer to zlib itself and to the official zlib and deflate documentation. Note that the specifications both achieved official Internet RFC status in May 1996, and zlib itself was adopted by JavaSoft in version 1.1 of the Java Development Kit (JDK), both as a raw class and as a component of the JAR archive format.
The lovely zlib-vise image above was provided courtesy of Bruce Gardner, art director of Dr. Dobb's Journal. It appears in Mark Nelson's article in the January 1997 issue (see below).
The source code for the current release version is publicly available for general use:
zlib source code, version 1.1.2, gzip'd tar format (121k):
US (California) (also via
ftp)
US (Virginia)
France
zlib source code, version 1.1.2, zipfile format (186k):
US (California) (also via
ftp)
US (Virginia)
France
Version 1.1.2 adds a number of new features, including contributed code; see the ChangeLog for details.
Note that zlib is an integral part of libpng and has been tested extensively as part of many PNG-supporting applications. Upcoming versions of gzip and UnZip will also use zlib.
zlib Documentation
zlib Technical Details
Mark Nelson's
ZlibTool article and
source code for
Dr. Dobb's Journal (January 1997)
zlib for
Windows 95/NT (DLL version, plus related utilities)
zlib for OS/2
(static version, plus related utilities and libraries)
zlib
32-bit OCX
(C++ source and binaries for use with Visual Basic 4.x or Delphi 2.0)
zlib Perl interface (source code; look for Compress-Zlib*.tar.gz)
zlib Python
interface (online manual; part of the standard library as of
Python 1.5)
zlib Tcl
interface (online manual; see chapter on ``Where to Get'')
zlib Java interface (see also JAR format)
Mark Nelson's
JavaZip article (with source code) for
Dr. Dobb's Journal (December 1997)
Gilles Vollant's zlib-based mini-zip and mini-unzip
Real World Scanning and Halftones
(second edition includes a section on zlib)
Markus Oberhumer's
LZO `real-time' data compression library
PPP Deflate Protocol
(RFC 1979)
Info-ZIP Home Page
Portable Network Graphics (PNG)
Home Page
gzip Home Page
Compression
Pointers
comp.compression Frequently Asked Questions list
Copyright © 1996-1998 Greg Roelofs.