Compression Utility
-------------------

For installation instructions, see the README file.

This is the "Compression Utility" for the TitanOS under
baseline 5 software.  It consists of a shell script, "arch"
that can be run by itself, from the command line to 
compress and uncompress files.  
There is also a user interface: "cmprss5" which will
read the files from the workbench, and bring up a window
on the screen for the user to click on either "Compress"
or "Uncompress".  The workbench files will then be 
processed by the arch script.  If you want more 
information on how to run arch from the command line 
(without the user interface), see the file arch.doc.

The user interface will handle up to 100 files.  If 
you put more than 100 files on the workbench, only the
first 100 will be processed.

cmprss5.c is written using HP widgets, and runs 
under baseline 5 software. We expect cmprss5 to have
a short life.  When baseline 7 software is released
all of the HP widgets will be changed to motif widgets,
and cmprss5 will no longer run.  But fear not, there 
is another version already running with motif widgets 
on the Odyssey VP's, and will be available to the 
Titans when BL7 is released.


DESCRIPTION:
Patient files on the Work Bench will be Compressed
or Uncompressed.  Compressed files will take much
less space on the disk for storage, but cannot be
processed or displayed.  The disk space required 
for a compressed file will be approximately 1/6
to 1/3 of the disk space required for the original
file.

If you run the Picker "cibuild" utility, the
compressed files will look normal, and there will
be no indication in the Clinical Index that the
files are compressed.

Compressed files can be transferred using the 
normal "Patient Transfer" Utility.  After transfer, 
the new files can be uncompressed by putting them 
on the Work Bench and using the Compression 
Utility.

Compression is applied to files in the following 
categories:  raw data, transverse reconstructions, 
oblique reconstructions, and lightboxes.  Other
types of files will not be compressed or 
uncompressed.

A patient subdirectory may contain a mixture of
compressed and uncompressed files.  This should
cause no problems, except the compressed files
must be uncompress to display or process.

The compression is performed by the standard unix
utility which uses adaptive Lempel-Ziv coding.


Good Luck!

--------------------------------
arch script written by:
Eugene Mah, MSc Graduate Student
(eugene@raddi.uah.ualberta.ca)

University of Alberta Hospitals
Edmonton, Alberta, Canada

--------------------------------
cmprss5 interface written by:
Wesley Wooten, Ph.D.   
(wooten@medisun.ucsfresno.edu)

Saint Agnes Medical Center
Fresno, California
--------------------------------