packJPG Usage Information

packJPG v2.4 (03/24/2010)
~~~~~~~~~~~~~~~~~~~~~~~~~

packJPG is a compression program specially designed for further
compression of JPEG images without causing any further loss. Typically
it reduces the file size of a JPEG file by 23%...24%.


Limited Free Use License Agreement & Copyright Notice
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

All packJPG software (the “Software”) which you download from this
website, or which is delivered to you by email or by any other means,
shall only be used for private non-commercial use and for non-commercial
research purposes. You shall never offer for sale or sell the Software
to any third party, whether in whole or in part or as an integrated
module or sub-module included or embedded in any other software
application or software bundle for any purpose of resale or commercial
gain. Any and all delivery and/or distribution of the Software by any
commercial entity or business is prohibited, whether such delivery
and/or distribution is free or not.

The Software, including all intellectual property rights, are the
exclusive joint property of HTW Aalen University and Matthias Stirner
(the “Owners”). The Owners disclaim all warranties with respect to the
Software. The Software is provided “as is” without any warranty. You are
using the Software at your own risk and responsibility. The Owners shall
never become liable to you or to any third party for any costs or
damages resulting from the use of the Software.

The Software is protected by German, United States and other foreign
copyright laws and international treaties. Any permitted copy of the
Software hereunder must always contain this entire copyright and license
notice. Please direct any inquiry about the Software to
packjpg@htw-aalen.de.

Copyright 2006...2010 by HTW Aalen University and Matthias Stirner.


Usage of packJPG
~~~~~~~~~~~~~~~~

JPEG files are compressed and PJG files are decompressed using this
command:

"packJPG [file(s)]"

packJPG recognizes file types on its own and decides whether to compress
(JPG) or decompress (PJG). For unrecognized file types no action is
taken. Files are recognized by content, not by extension.

packJPG supports wildcards like "*.*" and drag and drop of multiple
files. Filenames for output files are created automatically by changing
the file extension to ".pjg". In default mode, files are never
overwritten. If a filename is already in use, packJPG creates a new
filename by adding underscores.

If "-" is used as a filename input from stdin is assumed and output is
written to stdout. This can be useful for example if jpegtran
(http://jpegclub.org/) is to be used as a preprocessor.

Usage examples:

"packJPG *.pjg"
"packJPG lena.jpg"
"packJPG kodim??.jpg"
"packJPG - < sail.pjg > sail.jpg"


Command line switches
~~~~~~~~~~~~~~~~~~~~~

-ver verify files after processing
-v? level of verbosity; 0,1 or 2 is allowed (default 0)
-o overwrite existing files
-p proceed on warnings
-d discard meta-info

By default, compression is cancelled on warnings. If warnings are
skipped by using "-p", most files with warnings can also be compressed,
but JPEG files reconstructed from PJG files might not be bitwise
identical with the original JPEG files. There won't be any loss to
image data or quality however.

Unnecessary meta information can be discarded using "-d". This reduces
compressed files' sizes. Be warned though, reconstructed files won't be
bitwise identical with the original files and meta information will be
lost forever. As with "-p" there won't be any loss to image data or
quality.

There is no known case in which a file compressed by packJPG (without
the "-p" option, see above) couldn't be reconstructed to exactly the
state it was before. If you want an additional layer of safety you can
also use the verify option "-ver". In this mode, files are compressed,
then decompressed and the decompressed file compared to the original
file. If this test doesn't pass there will be an error message and the
compressed file won't be written to the drive.

Please note that the "-ver" option should never be used in conjunction
with the "-d" and/or "-p" options. As stated above, the "-p" and "-d"
options will most likely lead to reconstructed JPG files not being
bitwise identical to the original JPG files. In turn, the verification
process may fail on some files although nothing actually went wrong.

Usage examples:

"packJPG -v1 -o baboon.pjg"
"packJPG -ver lena.jpg"
"packJPG -d tiffany.jpg"
"packJPG -p *.jpg"


Known Limitations
~~~~~~~~~~~~~~~~~

packJPG is a compression program specially for JPEG files, so it doesn't
compress other file types.

packJPG has low error tolerance. JPEG files might not work with packJPG
even if they work perfectly with other image processing software. The
command line switch "-p" can be used to increase error tolerance and
compatibility.

If you try to drag and drop too many files at once, there might be a
windowed error message about missing privileges. In that case you can
try it again with less files or consider using the command prompt.
packJPG has been tested to work perfectly with thousands of files from
the command line. This issue also happens with drag and drop in other
applications, so it might not be a limitation of packJPG but a
limitation of Windows.

Compressed PJG files are not compatible between different packJPG
versions. You will get an error message if you try to decompress PJG
files with a different version than the one used for compression. You
may download older versions of packJPG from:
http://www.elektronik.htw-aalen.de/packjpg/packjpg_m.htm


Self extracting archives
~~~~~~~~~~~~~~~~~~~~~~~~

A seperate executable ("packJPX.exe"), capable of creating self
extracting (SFX) archives, is included in the packJPG package for
Windows only. Using packJPX, it's possible to share a collection of
packJPG compressed JPEG images while not requiring the receiver to
download the packJPG application. packJPX compresses one or more files
to a portable .EXE file using this syntax:

"packJPX [name of SFX archive] [file(s) to compress]"

Archives created by packJPX are self contained and will extract their
contents to the path of the archive upon execution. No file will ever be
overwritten in this process. If a filename is already in use, a new
filename is created by adding underscores.

Other than packJPG, packJPX will process and add any file type to the
archive. Only JPEG image files are actually compressed by packJPX, all
other file types will be stored, not compressed, inside the archive. As
there won't be any reduction in size for these, it is not advised to add
large quantities of non-JPEG files to a packJPX created self extracting
archive.

Usage examples:

"packJPG sfx.exe lena.jpg readme.txt"
"packJPG sfx.exe *.jpg"

Please note that, although being well-tested without any problems having
been found so far, packJPX is still in beta stage and shouldn't be used
for backup of important data. As of packJPG v2.4, development on packJPX
will be discontinued and there won't be a Unix compatible version
either. A similar application with extended functionality is already in
the works and will eventually be released for both Windows and Unix.


History
~~~~~~~

v1.9a (04/20/2007) (non public)
- first released version
- only for testing purposes

v2.0 (05/28/2007) (public)
- first public version of packJPG
- minor improvements to overall compression
- minor bugfixes

v2.2 (08/05/2007) (public)
- around 40% faster compression & decompression
- major improvements to overall compression (around 2% on average)
- reading from stdin, writing to stdout
- smaller executable
- minor bugfixes
- various minor improvements

v2.3 (09/18/2007) (public)
- compatibility with JPEG progressive mode
- compatibility with JPEG extended sequential mode
- compatibility with the CMYK color space
- compatibility with older CPUs
- around 15% faster compression & decompression
- new switch: [-d] (discard meta-info)
- various bugfixes

v2.3a (11/21/2007) (public)
- crash issue with certain images fixed
- compatibility with packJPG v2.3 maintained

v2.3b (12/20/2007) (public)
- some minor errors in the packJPG library fixed
- compatibility with packJPG v2.3 maintained

v2.4 (03/24/2010) (public)
- improved compression: typical file size reduction is now 23%...24%
- around 10% faster compression & decompression
- major improvements to JPG compatibility
- UPX compression removed due to false alerts in virus scanners
- new switch: [-ver] (verify file after processing)
- new switch: [-np] (no pause after processing)
- new progress bar output mode
- arithmetic coding routines rewritten from scratch
- various smaller improvements to numerous to list here
- new SFX (self extracting) archive format


Acknowledgements
~~~~~~~~~~~~~~~~

packJPG is the result of countless hours of research and development. It
is part of my final years project for Hochschule Aalen.

Prof. Dr. Gerhard Seelmann from Hochschule Aalen supported my
development of packJPG with his extensive knowledge in the field of data
compression. Without his advice, packJPG would not be possible.

Michael Lee is the author "packJPG Options", the first official Windows
GUI for packJPG and packJPX. Pay him a visit at his website
http://www.phototools.co.nr/packjpg-options/ and be sure to also check
out his other great tools!

The official homepage of packJPG is currently maintained by Hochschule
Aalen staff.

packJPG logo and icon are designed by Michael Kaufmann.


Contact
~~~~~~~

The official home of packJPG:
http://www.elektronik.htw-aalen.de/packjpg/

For questions and bug reports:
packjpg (at) htw-aalen.de


____________________________________
packJPG by Matthias Stirner, 03/2010