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Frequently Asked Questions in comp.lang.postscript
 
No warranty is made as to the validity of the answers below.
I don't work for any of these companies, and I've used only
some of these products, so there will probably be minor
errors.  I welcome corrections.
 
If you think of questions appropiate for this FAQ, or would
like to improve on an answer, please email me at the address
below.
 
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What is EPS?
How do I convert PS to EPS?
 
EPS (Encapsulated PostScript) is a PostScript language program
that is limited to a subset of the language suitable for
inclusion in a document as an illustration.
 
In order to meet this requirement, the program must leave the
interpreter in the same state it was in at the program's
beginning (ie. all stacks returned to their original contents,
the graphics state back where it was, and any memory (VM)
consumed by the program has been released).  The EPS program
must not use operators that initialize or permanently change
the state of the machine.  As a special case, the EPS program
may use the showpage operator.  The importing application is
responsible for disabling the normal effects of showpage. Note
that only one call to showpage may appear in the program (ie.
the program generates one page of output).
 
The EPS program should make no environment-sensitive decisions
(the importing application may be trying to attain some special
effect, and the EPS program shouldn't screw this up), although
it can use some device-dependent tricks to improve appearance
such as a snap-to-pixel algorithm.
 
Additionally,  the program must have an identifying comment at
the top indicating that it is a conforming program, and a
comment specifying the region on the page that is changed (the
"BoundingBox" comment).
 
The complete EPS specification is available from Adobe (see
below).
 
A variation of EPS embeds the PS text in a binary file which
contains a header and either a TIFF or MetaFile preview image.
The header defines where in the file each section (EPS, TIFF,
or MetaFile) starts and ends.  On the Macintosh, the preview
is stored as a PICT in the file's resource fork.
 
To convert from PS to EPS, one must guarantee that the PS file
meets the above requirements.  If the actual program conforms
to the programming requirements, then one can simply add the
required comments at the top of the file saying that the file
is EPS and giving its BoundingBox dimensions.
 
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How can I convert PS to [other graphics format]?
How can I convert [other graphics format] to PS?
How can I display PS on my [brand x] computer?
 
Since PostScript is not just a picture-description language,
but in fact a complete programming language, one needs a
complete PostScript interpreter to convert or display a
PostScript graphic. Adobe PostScript interpreters are available
for some machines (notably those using the NextStep GUI).  
 
Numerous PostScript interpreter clones, both commercial and
free, are available for other machines.  Not all clone
interpreters know how to handle Adobe's encrypted Type 1 fonts,
and some have other incompatibilities.  Clone interpreters will
not have Adobe's proprietary rendering technology which
interprets font hints to improve the appearance of fonts shown
at small sizes on low-resolution devices.
 
Ghostscript, a freeware product associated with the GNU
project, is available for PC's, Sun's, X servers, and other
architectures.  Source is included.  For more information about
Ghostscript, read the gnu.ghostscript newsgroup, or contact the
author at ghost@aladdin.com (L. Peter Deutsch).
 
Sun Open Look users can use Sun's NeWs or a new Sun Sparc-based
interpreter for driving non-PostScript printers (I forget the
product name).
 
MSDOS users can use Go-Script, QMS UltraScript-PC, or Freedom
of the Press.  File format conversion is available with
Hijack-PS.
 
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What documentation is available on the PostScript language?
 
Adobe has written numerous manuals, sometimes referred to
by PostScript gurus by the color of the cover.  These books
are published by Addison-Wesley.  They are listed here in
order of (my) suggested reading:
 
PostScript Language Tutorial and Cookbook ("The Blue Book")
PostScript Language Reference ("The Red Book")
PostScript Language Program Design ("The Green Book")
Adobe Type 1 Font Format ("The Black Book")
 
Books published outside of Adobe include:
 
Real World PostScript ("The Orange Book")
Inside PostScript ("The White Book")
Thinking in PostScript
 
A new edition of the red book is scheduled to be released about
December 1990 which will incorporate features of Display
PostScript, advanced color handling, and new features added to
the language since the first edition.
 
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How do I get bitmap representations of Adobe fonts?
 
Use the Font Foundary program included with the font.  If you
don't have it, contact Adobe for an upgrade.
 
================================================================
 
How do I get in touch with Adobe?
 
Adobe Systems Incorporated
1585 Charleston Road
P.O. Box 7900
Mountain View, CA 94039-7900
 
Phones:
Main:           (415)961-4400
Tech Support:   (415)961-0911
Developers Line & Tech Docs (voice mail):
                (415)961-4111
Sales:          (800)344-8335
 
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Ken (shiva@well.sf.ca.us)
"Pay no attention to that man behind the curtain!"