[KLUG Members] Re: Those grainy postscript files... -- Ghostscript/ps2pdf is a hack!

[Bryan J. Smith]

On Mon, 2002-03-18 at 20:21, Tony Gettig wrote:
> When I print, no matter if it's to the humble Lexmark 3200 inkjet at
> home or to the HP Laserjet 4050 at work, the job comes out grainy.

If you're talking fonts, it's probably because your program is
outputting at a low DPI resolution.

Unless you aren't talking just fonts, but grayscale backgrounds and
other fills.  That would also be an application issue where it is using
a poor choice.

It could also be the Postscript emulation in Ghostscript, unless those
printers are Postscript native.  If they are (I though at least the 4050
is?), I'd say you have your Postscript settings at far too low of a
resolution.  If they aren't, the PCL5 -> PS emulation in Ghostscript has
been "good enough" in my experience, so you should be seeing good
results on your LaserJet 4050.

I'm using 600dpi on my Lexmark Optra e310 and HP LaserJet 1220 (both
Postscript Level 2 native) and getting _excellent_output_ in both Linux
and Windows.  Even at 300dpi, Ghostscript does a good job on my
non-Postscript/PCL4 HP DeskJet 870Cse too.

> Additionally, if I print to a postscript file, run it through ps2pdf, I
> get the same result: a grainy looking PDF file. The text is OK, but any
> kind of graphic looks shabby.

Although that _may_ be the same issue, it is not always.

Understand that ps2pdf is a Ghostscript "hack" that doesn't support much
of PDF.  As such, most fonts are stored as "bitmaps" in a ps2pdf run so
they look like crap on-screen.  But usually they output to a good
resolution in hardcopy (because they are usually high DPI bitmaps).

It sounds like your application is using a poor DPI resolution in the
case of fonts, or poor fills in the case of graphics/backgrounds.

> If I print a PDF I grab from the Internet (open in xpdf, print to ps
> file, send to printer), it's perfect. 

Of course!  Most "professional/technical" PDF publications are created
in Adobe FrameMaker or Aldus (now Adobe) PageMaker.  Adobe created
Postscript and PDF, so their applications produce nice and native PDFs. 
Other PDFs are created with Adobe Distiller for Mac and Windows and are
almost as nice.

ps2pdf is a _total_hack_ in comparison.  It takes Postscript and
generates largely PDF bitmaps and simple Postscript attributes, instead
of native PDF with complex Postscript vectors and attributes.

The only Open Source applications that produce "native" PDFs are based
on the TeX typeset and, increasingly, DocBook languages.  E.g., the LyX
WYSIWYM GUI for TeX/DocBook.

> From the reading I've done so far, I'm thinking I need to tweak
> something in my ghostscript setup. Any suggestions? 

Sounds like your Ghostscript filters for your printers are not setup
correctly.  What distro?  I've always found RedHat's "printtool" to be
excellent, allows me to setup the correct DPI.

-- Bryan

-- 
Don't confuse the US Constition with its Bill Of Rights.
One was written by legislators, the other by its people.
--------------------------------------------------------
Bryan J. Smith, Engineer       mailto:b.j.smith@ieee.org
SmithConcepts, Inc.         http://www.SmithConcepts.com
       Consulting Engineers and IT Professionals