Welcome to Linux Knowledge Base and Tutorial
"The place where you learn linux"
Let The Music Play: Join EFF Today

 Create an AccountHome | Submit News | Your Account  

Tutorial Menu
Linux Tutorial Home
Table of Contents

· Introduction to Operating Systems
· Linux Basics
· Working with the System
· Shells and Utilities
· Editing Files
· Basic Administration
· The Operating System
· The X Windowing System
· The Computer Itself
· Networking
· System Monitoring
· Solving Problems
· Security
· Installing and Upgrading
· Linux and Windows

Glossary
MoreInfo
Man Pages
Linux Topics
Test Your Knowledge

Site Menu
Site Map
FAQ
Copyright Info
Terms of Use
Privacy Info
Disclaimer
WorkBoard
Thanks
Donations
Advertising
Masthead / Impressum
Your Account

Communication
Feedback
Forums
Private Messages
Surveys

Features
HOWTOs
News Archive
Submit News
Topics
User Articles
Web Links

Google
Google


The Web
linux-tutorial.info

Who's Online
There are currently, 288 guest(s) and 4 member(s) that are online.

You are an Anonymous user. You can register for free by clicking here

  

HOWTO Home

Current HOWTO: Printing-HOWTO


Ghostscript.

10. Ghostscript.

Ghostscript is an incredibly significant program for free software-driven printing. Most printing software under Unix generates PostScript, which is typically a $100 option on a printer. Ghostscript, however, is free, and will generate the language of your printer from PostScript.

Ghostscript is available in several forms. The commercial version of Ghostscript, called Aladdin Ghostscript, may be used freely for personal use but may not be distributed by commercial entities. It is generally a year or so ahead of the free Ghostscript; at the moment, for example, it supports many color inkjets that the older Ghostscripts do not and has rather better PDF support.

The main free version of Ghostscript is GNU Ghostscript, and is simply an aged version of Aladdin ghostscript. This somewhat awkward arrangement has allowed Aladdin to be a totally self-funded free software project; the leading edge versions are done by L Peter and a few employees, and are licensed to hardware and software vendors for use in commercial products. Unfortunately, while this scheme has provided for L Peter's continued work on Ghostscript for years, it has also inhibited the participation of the wider free software community. Driver authors, in particular, find the arrangement poor. L Peter's retirement plans mandate a larger community involvement in the project, so he is considering license changes, and has established a SourceForge project.

The third version of Ghostscript is ESP Ghostscript, maintained by Easy Software Products (authors of CUPS) under contract from Epson. ESP Ghostscript is a combination of the gimp-print driver project's drivers and GNU Ghostscript, plus assorted usability patches. This version is not yet in full swing, but it will be available soon, and will hopefully simplify life for owners of Gimp-print-driven printers.

Whatever you do with gs, be very sure to run it with the option for disabling file access (-dSAFER). PostScript is a fully functional language, and a bad PostScript program could give you quite a headache.

Speaking of PDF, Adobe's Portable Document Format (at least through 1.3) is actually little more than organized PostScript in a compressed file. Ghostscript can handle PDF input just as it does PostScript. So you can be the first on your block with a PDF-capable printer.

10.1. Invoking Ghostscript

Typically, Ghostscript will be run by whatever filter you settle upon (I recommend Foomatic if your vendor didn't supply anything that suits you), but for debugging purposes it is often handy to run it directly.

gs -helpwill give a brief listing of options and available drivers (note that this list is the list of drivers compiled in, not the master list of all available drivers).

You might run gs for testing purposes like: `gs <options> -q -dSAFER -sOutputFile=/dev/lp1 test.ps'.

10.2. Ghostscript output tuning

There are a number of things one can do if Ghostscript's output is not satisfactory (actually, you can do anything you darn well please, since you have the source).

Some of these options, and others are described in the Ghostscript User Guide (the file Use.htm in the Ghostscript distribution; possibly installed under /usr/doc or/usr/share/doc on your system) are all excellent candidates for driver options in your filter system.

10.2.1. Output location and size

The location, size, and aspect ratio of the image on a page is controlled by the printer-specific driver in ghostscript. If you find that your pages are coming out scrunched too short, or too long, or too big by a factor of two, you might want to look in your driver's source module and adjust whatever parameters jump out at you. Unfortunately, each driver is different, so I can't really tell you what to adjust, but most of them are reasonably well commented.

10.2.2. Gamma, dotsizes, etc.

Most non-laser printers suffer from the fact that their dots are rather large. This results in pictures coming out too dark. If you experience this problem with an otherwise untunable driver, you could use your own transfer function. Simply create the following file in the ghostscript lib-dir and add its name to the gs call just before the actual file. You may need to tweak the actual values to fit your printer. Lower values result in a brighter print. Especially if your driver uses a Floyd-Steinberg algorithm to rasterize colors, lower values ( 0.2 - 0.15 ) are probably a good choice.


%!
%transfer functions for cyan magenta yellow black
{0.3 exp} {0.3 exp} {0.3 exp} {0.3 exp} setcolortransfer


It is also possible to mend printers that have some kind of color fault by tweaking these values. If you do that kind of thing, I recommend using the filecolorcir.ps, that comes with ghostscript (in the examples/ subdirectory), as a test page.

For many of the newer color inkjet drivers, there are command-line options, or different upp driver files, which implement gamma and other changes to adapt the printer to different paper types. You should look into this before playing with Postscript to fix things.

10.2.3. Color Printing in Ghostscript

Ghostscript's default color dithering is optimized for low-resolution devices. It will dither rather coarsely in an attempt to produce 60ppi output (not dpi, ppi - the "apparent" color pixels per inch you get after dithering). This produces rather poor output on modern color printers; inkjets with photo paper, in particular, are capable of much finer ppi settings.

To adjust this, use the Ghostscript option-dDITHERPPI=x, where x is the value to use. This may or may not have an effect with all drivers; many newer drivers (the Epson Stylusstp driver, for example) implement their own dithering and pay no attention to this setting. Some drivers can use either the regular Ghostscript or driver-specific dithering (the Canon Bubblejet bjc600 driver, for example).

Ghostscript's dithering is in fact rather rudimentary. Many things needed for good output on modern printers are simply not available in the Ghostscript core. Various projects to fix this situation—and the free software world does have the software to do so ready and waiting—are hampered by Ghostscript's licensing situation and the resulting "cathedral" development style. Beginning at the Open Source Printing Summit 2000, however, all the necessary people are talking, so you can expect this situation to improve shortly.


The Linux Tutorial completely respects the rights of authors and artists to decide for themselves if and how their works can be used, independent of any existing licenses. This means if you are the author of any document presented on this site and do no wish it to be displayed as it is on this site or do not wish it to be displayed at all, please contact us and we will do our very best to accommodate you. If we are unable to accommodate you, we will, at your request, remove your document as quickly as possible.

If you are the author of any document presented on this site and would like a share of the advertising revenue, please contact us using the standard Feedback Form.


  
Show your Support for the Linux Tutorial

Purchase one of the products from our new online shop. For each product you purchase, the Linux Tutorial gets a portion of the proceeds to help keep us going.


Login
Nickname

Password

Security Code
Security Code
Type Security Code


Don't have an account yet? You can create one. As a registered user you have some advantages like theme manager, comments configuration and post comments with your name.

Help if you can!


Amazon Wish List

Did You Know?
You can get all the latest Site and Linux news by checking out our news page.


Friends



Tell a Friend About Us

Bookmark and Share



Web site powered by PHP-Nuke

Is this information useful? At the very least you can help by spreading the word to your favorite newsgroups, mailing lists and forums.
All logos and trademarks in this site are property of their respective owner. The comments are property of their posters. Articles are the property of their respective owners. Unless otherwise stated in the body of the article, article content (C) 1994-2013 by James Mohr. All rights reserved. The stylized page/paper, as well as the terms "The Linux Tutorial", "The Linux Server Tutorial", "The Linux Knowledge Base and Tutorial" and "The place where you learn Linux" are service marks of James Mohr. All rights reserved.
The Linux Knowledge Base and Tutorial may contain links to sites on the Internet, which are owned and operated by third parties. The Linux Tutorial is not responsible for the content of any such third-party site. By viewing/utilizing this web site, you have agreed to our disclaimer, terms of use and privacy policy. Use of automated download software ("harvesters") such as wget, httrack, etc. causes the site to quickly exceed its bandwidth limitation and are therefore expressly prohibited. For more details on this, take a look here

PHP-Nuke Copyright © 2004 by Francisco Burzi. This is free software, and you may redistribute it under the GPL. PHP-Nuke comes with absolutely no warranty, for details, see the license.
Page Generation: 0.12 Seconds