Welcome to the packJPG Homepage

Note (Feb 26, 2013):

The most recent versions of packJPG and packARC are available from the authors website
(always up-to-date): http://www.matthiasstirner.com/ 
or https://www.dropbox.com/sh/ge0pownduiv9oqq/y3q2KKFsJq

There's also an official GUI for packJPG 2.5 under Microsoft Windows,
see Michael Lee's "packJPG Options" on his website!

Recenty added (Feb 26, 2013):  V2.5f

packJPG v2.5e now released under the LGPL.

It is now open source under the terms of LGPL v3 (previous licensing was GPL v3).

The package includes the Microsoft Windows binary, documentation and source code.

Improvements over packJPG v2.5a (last public version):
- fixed a rare bug with progressive JPEG files
- further removal of redundant code
- various source code optimizations
- some fixes for the packJPG static library
- compiler fix for Mac OS (thanks to Sergio Lopez)
- improved compression ratio calculation
- eliminated the need for temp files
- moved packARC to a separate package

Versions 2.5a of packJPG and 2.5e are meant to be fully compatible.
Version 2.5a can uncompress files created by 2.5e and vice versa.
The compression ratio of version 2.5e is the same as that of version 2.5a.

Download the improved package here!

  W A R N I N G  !!!   (12-03-30)


There is a bug in the archiver application packARC (Frontend v0.2 / Library v0.3a).

It will happily create archives larger than 2GB, but - due to using C functions ftell() and fseek() - it cannot extract, test, or list files from archives larger than 2GB.

Theoretically, packJPG is also affected , but it is extremely unlikely that it will hit the 2 GB limit. Please remember to test always the correctness of your compressed files before deleting the original data !

We are working on a recovery program for the archiver problem.

Sorry, for any inconvenience we may have caused.

Newly added (December 22, 2011):  V2.5a

  This version 2.5a is compatible with version 2.5.
The changes between version 2.5 and 2.5a are meant to improve
the build process in particular using g++ version 4 and under Linux.
Download the improved package here!


Latest Binary Releases of packJPG:  V2.5

packJPG 2.5 is now open source and available for download.
Along with the windows binaries, source code is included in the archive
to be used under the terms of the GPL v3.

Improvements over v2.4:

 - increased overall compression (~0.5%)
 - several minor bugfixes
 - major code cleanup
 - removed packJPX from the package
 - added packARC to the package
 - packJPG is now open source!

Download packJPG 2.5 Source Code incl. Windows Executable.

Older Files are available here.

November 15, 2011

Lossless Compression for PNM-Image Files:

  • packPNM is a state-of-the-art lossless compression software for PNM (PPM/PGM/PBM) images.
    It is more or less an experiment wether parts of the packJPG algorithm could be reused for different, non DCT based image types as well. packPNMs compression ratios are varying, but are typically quite good in comparison to other approaches, especially for binary (PBM) images.
    We release packPNM and its source code (to be used under the terms of the GPL v3) alongside packJPG v2.5.
    Download packPNM 1.0e Source Code incl. Windows Executable!

JPEG Open Source Developers Package:

November 16, 2011

Notes and Papers:
Jan 31, 2008 / Apr 20, 2010