Q: Postscript and PDF

In article 
<Pine.OSF.3.95.970327181203.26322B-100000 at poseidon.ifctr.mi.cnr.it> you wrote:
: Please reply also by e-mail since I won't be reading news during coming Easter
: holidays !

:   - what would be the advantages and disadvantages of using PDF compared
:     with postscript ?

PDF was designed to overcome portability problems of PostScript.  It is
much more tightly controlled, and also has some features that make 
viewing more efficient (a table of offsets so the browser can jump to
a page quickly).  The files are binary, so a bit more care is needed in
sending them around.  

If you aren't having problems with PS files, PDF is not so important.
The Adobe viewers are pretty good on the platforms that support them, 
on other platforms (OS/2 2.1, some flavors of unix) you use ghostview
or one of several other viewers.

:   - what are the implication in terms of word processors (as far as I know
:     MS Word or Latex can't produce it ; otherwise said, how is it generated ?)

There is a new tex that can write PDF directly, or dvi.  Currently it
only handles PNG graphics, but people are working to support EPS and
other formats.  Once this is working there will really be no reason for many 
people to continue using .dvi files at all with TeX.  The other problems are
the lack of suitable fonts (e.g., type 1 ec fonts) for some people 
and tools to replace dvicopy, etc. for reordering pages, etc.

Adobe Distiller is the mainstream way, and it can be used with dvips
if you get type 1 fonts.  There is a pdfwrite device in ghostscript,
but it only supoprts the base Adobe fonts, and converts others to 
bitmaps or outline paths.  Actually, it works quite well for docs
that have only a little math if you use Times-Romand for the text font.
I have used it for a number of texinfo manuals, and the results were 
quite useful.

With Word, you can install a printer drive that creates PS (part of
the Adobe distiller package).  Many people have reported that some
documents are converted to a raster format, which is also a problem
with the PS driver.  Maybe this has been fixed on the Win32 versions.
 
:   - what are the implications in terms of printing ? does one need to convert
:     to postscript to print it on the current printers ?

You generally print from the viewer, which adds a header and strips some
unwanted info.

--
George White <aa056 at chebucto.ns.ca> <gwhite at bionet.bio.dfo.ca>

From: Uri Blumenthal <NOSPAM!uri at ibm.net>
Newsgroups: comp.lang.postscript
Subject: Re: Q: Postscript and PDF
Date: 30 Mar 1997 15:25:09 -0500
Xref: leonardo.area.mi.cnr.it comp.lang.postscript:7278

>>>>> "Peter" == Peter Davis <pd at world.std.com> writes:

    >> - what would be the advantages and disadvantages of using PDF
    >> compared with postscript ?

    Peter> PDF can be thought of as a dialect of PostScript.  It was
    Peter> developed to use the PostScript imaging model, but to
    Peter> define a subset of the language which could be easily
    Peter> parsed and understood by applications without requiring a
    Peter> full-blown PostScript interpreter.

Yes. That was [is?] the intention.
But the rest of the stuff you got exactly backward, I think.

    Peter> Not everyone can read/print PostScript files..........
    Peter> PDF, on the other hand, can be viewed and printed with a
    Peter> free utility...............

Not everyone can read/print PDF, as there's no printer capable
of dealing with PDF directly and you have to have special
software to do the viewing and conversion. The most
widely known viewers are: Adobe AcroRead (available for
several platforms free), Aladdin Ghostscript (free,
runs on practically any platform) and xpdf (still somewhat
buggy, especially wrt. PDF-1.2). 

Now to print PDF - well, that's the problem, since no
printer undertstands it yet. AcroRead will convert it
to Postscript for you though.

At *this* time, there is no well-established way to WRITE
PDF. One can use Ghostscript to convert Postscript to PDF,
but the quality of the resulting PDF file is not great.Or
one can buy Adobe Acrobat (or Exchange or whatever the 
correct name is - sorry I don't recall, nor do I really
care) for (if my memory serves me) $295.

On the other hand, anybody can read/print/write Postscript,
as there's lots of freely available software to do so plus
many printers on the market can print Postscript files
directly - user just needs to send that file to the
printer, and - unlike PDF - it will end up on the paper.


           ...........[AcroRead from Adobe].............
    Peter> This is available for Macs, Windows, and (I believe) many
    Peter> flavors of Unix.

Yeah, while Postscript software is available for Macs, MS DOS,
Windows, practically all Unix flavors, VMS, and most of the
laser printers.

    Peter> Some word processors are able to generate PDF.  In other
    Peter> cases, a separate utility is needed.

While practically all the word processors are able to generate
Postscript; Postscript driver is included in the Windows and
Macs were Postscript-based since ages.


    Peter> If all the readers of your documents are also producers,
    Peter> there may be no advantage to PDF, since you need PostScript
    Peter> capable utilities to produce it anyway.

Again, not really. There is at least one project (pdftex) that
produces PDF directly. However, today indeed, in order to get
PDF you would have to produce Postscript first.

    Peter> PDF wins in a
    Peter> situation where you have a few authors, who can be equipped
    Peter> with the appropriate utilities so that a large number of
    Peter> people can read the documents with freely available
    Peter> software.

Definitely not true. Because even more widely available free
software allows viewing and printing Postscript, and most
likely your large number of people *already has* that
Postscript-reading software (unlike PDF, mind you!).

    >> - what are the implications in terms of printing ? does one
    >> need to convert to postscript to print it on the current
    >> printers ?

Of course! 

[Or, if the printer does not understand Postscript, like several 
cheaper models nowadays, you would have to convert your Postscript 
to the printer native language.]

    Peter> The Acrobat viewer can print PDF documents.

Oh yeah? 

The Acrobat viewer can convert PDF file to Postscript and spool
it to the printer. Now - if your printer understands Postscript,
all good and well. Otherwise - you guessed it.