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From: josh at turb01.dmc.com
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To: grassu-list at max.cecer.army.mil, <gibb at hubers.cecer.army.mil>
Subject: Postscript
X-Mailer: <PC Eudora Version 1.4>

As in many languages, there is postscript and there is postscript. Many 
programs such as pbmplus of image alchemy can convert images (pixelmaps) to 
and from postscript format. But this is not vector format. Ghostscript can 
convert a "vector" postscript file to an image but not back. The native 
"vector" or "object-oriented" file formats for Adobe Illustrator and 
Interviews idraw are true "postscript" in that you can dump the file 
directly to a postscript printer. However both of these are very specialized 
dialects of postscript, and neither program can read / edit an arbitrary 
postscript file. Rumor has it that a new version of Illustrator (5.5?) will 
be able to read in and edit the Adobe Exchange format of postscript. It may 
be that the "Exchange" dialect of postscript can be created from any 
arbitrary postscript by Adobe Acrobat Distiller (this may require a 
postscript printer or other licensed interpreter to function). If this 
capability does exist, then any arbitrary postscript file will be editable 
by Illustrator...for a price.

At present, the most practical means of editing postscript images on a 
workstation is a text editor side by side with either ghostview or xpsview 
(Display Postscript), and practical knowledge of the particular postscript 
dialect used by whatever produced your postscript file. Fortunately, most 
programs with a postscript output option rather than a postscript basis 
generate fairly simple forms of postscript without the extensive convoluted 
nests of macros and definitions typical of a Mac or Windows (or Illustrator 
or Canvas) postscript file.

Another practical step would be output files in the idraw form of 
postscript, but in most cases this would mean completely rewriting the 
postscript output routines such as ps.map...

It's surprising that no one has made more of an effort at an editing or 
conversion program which takes off from ghostscript's postscript parsing 
abilities, but I do not know of any to date. Any volunteers?

Cheers,

Joshua Lieberman, Ph.D.
ENSR Consulting and Engineering
josh at turb01.dmc.com
Joshua Lieberman, Ph.D.                josh at turb01.dmc.com
ENSR Consulting and Engineering        wasser at world.std.com
35 Nagog Park,  Acton, MA 01720        508-635-9500