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From: fp0a+@andrew.cmu.edu (F. Pierce, III)
Newsgroups: comp.lang.postscript
Subject: Re: Encapsulated Postscript to Postscript
Message-ID: <EXIMn-J38k-0A6VVEc@andrew.cmu.edu>
Date: 11 Oct 88 04:23:38 GMT
References: <415@pyuxf.UUCP>,
	<897@galaxy>
Distribution: na
Organization: Carnegie Mellon
Lines: 37
In-Reply-To: <897@galaxy>

Encapsulated Postscript is a file protocol which contains both
postscript code to generate an image and a screen bitmap of the same
image.  The idea is that programs can generate EPSF files for other
programs to import; the importing program displays the bitmap on
screen and then prints the postscript portion of the EPSF to the
printer later on.  (An example is Adobe Illustrator, which can
generate EPS files. Aldus Pagemaker can import those files during page
composition.)

On a Mac, the screen bitmap is stored as a PICT resource in the EPSF
file.  To convert to text -- that is, to extract the "raw" postscript
-- just use ResEdit to delete the PICT resource and convert the file
type from "EPSF" to "TEXT."  Converting EPSF to postscript on a PC
may be a bit trickier; I'll let somebody else handle it.

Oh, an interesting note:  A postscript file that conforms to Adobe's
EPSF structuring conventions doesn't need a screen representation.  In
the EPSF standard supplement (I forget the full name), Adobe
highlights the fact that the PICT resource on a Mac is optional.
Obviously, without it the importing program won't be able to give a
screen representation of the EPSF, but normally this isn't that much
of a problem.  Pagemaker, for instance, just displays a grey box.  And
Adobe has decreed that importing programs must be able to recognize
TEXT-type files as EPSF provided they conform to the structuring
conventions.  So you don't need to change the file type to EPSF to
import postscript code.

The current EPSF structuring conventions are available via Adobe's
mail server.  To figure out how to access the server, send a message
containing the line "send help" to adobe!ps-file-server@decwrl.dec.com.

Hope this helps.

--Howdy Pierce
  Carnegie Mellon University

  fp0a+@andrew.cmu.edu