Path: utzoo!attcan!uunet!snorkelwacker!apple!sun-barr!newstop!sun!angel!henry
From: henry@angel.Sun.COM (Henry McGilton--Software Products -- R.I.P.)
Newsgroups: comp.lang.postscript
Subject: Re: EPS and PS, the difference?
Summary: EPS Is A State Of Mind
Message-ID: <133322@sun.Eng.Sun.COM>
Date: 22 Mar 90 17:57:31 GMT
References: <1816@diamond2.UUCP>
Sender: news@sun.Eng.Sun.COM
Distribution: comp
Lines: 74

In article <1816@diamond2.UUCP>, derosa@motcid.UUCP (John DeRosa) writes:
    *  I am hot on the trail of a way to convert Sun Interleaf
    *  to Macintosh Pict.  I thought I had the problem licked
    *  but have reached another road block.
    *  
    *  I have converted the Interleaf file to PS.  What I mean
    *  by PS (postscript) is I have a file that is pure postscript
    *  code starting with #! Adobe.
That should read something like   %!PS-Adobe
    *  I then FTP'd the file
    *  to the Mac and was able to print the file with programs
    *  like Widgets and Postility.
    *  
    *  Postility also says it can convert EPS (encapsulated postscript)
    *  to Pict or Text.  This did nothing with my PS Interleaf file.
    *  
    *  The question is; what is PS, and what is EPS?  Can one
    *  be converted to the other?  Does anyone know the solution
    *  to my conversion problem.  Thanks in advance for any help.
EPS (Encapsulated PostScript) is more a state of mind than anything
magic.  Briefly, a file claiming to be EPS follows certain well
defined rules to ensure that when it is included into another PostScript
file, it does nothing to disturb the environment of the including
PostScript program.  An EPS file has one important item of
information, namely, a  %%BoundingBox  comment, that is not
necessarily present in a `regular' PostScript program.  A EPS
file can also contain an optional preview section so that an 
including application can display on your screen an approximation
of what the final printed image will look like.

`Converting' PS to EPS would consist of, at a minimum, inserting
a  %%BoundingBox  comment.  One of the best ways to find out
your bounding box, as was well flogged in this forum a few months
ago, is to print the picture and measure it with a ruler.

Note that many applications claiming to emit EPS do so in
ways that will break the including application, or will
fail to print.

    *  
    *  SIDE ISSUE: If I have a PS file from Interleaf, I can 
    *  print it on the sun with the lpr command and I get the 
    *  picture/document (not the PS code).  If I try the 
    *  same file on the mac and print it with a text editor
    *  like Edit, I get the PS code printout, not the 
    *  picture/document (downloading it with Widgets works
    *  fine).  Why the difference?
Chances are some prolog file is missing from the Mac version.
    *  
    *  SECOND SIDE ISSUE:  A Macintosh PS file begins with 
    *  the line #! Adobe 2.0,
I am sure that should be  %!PS-Adobe 2.0
    *  a Sun Interleaf PS file begins with the line #! Adobe.
I am sure that should be  %!PS-Adobe
    *  Does this mean that they are
    *  different versions of PostScript?  The Sun file will
    *  print on the Mac but the Mac file will NOT print on
    *  the Sun. 
I suspect that this is done to work around `deficiciencies'
in the version of TranScript shipped with the Sun system.
If a PS file starts with  %!PS-Adobe 2.0 or whatever, TranScript
may attempt to perform page reversal on the file.  The
version of TranScript shipped with Sun doesn't correctly
handle PostScript programs included inside other PostScript programs.
There's supposed to be a  %%BeginDocument / %%EndDocument
convention to stop the page reversal program from trying to
reverse pages in included documents, but TranScript doesn't
implement this feature, so psrev breaks.

	........  Henry
| Henry McGilton    |                      |                           |
| Sun Microsystems  | I saw the future,    | arpa: hmcgilton@sun.com   |
| 2550 Garcia       |  and it didn't work. | uucp: ...!sun!angel!henry |
| Mountain View, CA |                      |                           |