Working with a Printer

Most people have problems with printing, especially when they’re in a hurry. Unfortunately, dubious computer software and a slow mechanical device don’t always make a good combination.

Getting a Printer to Work

Before using your printer you must of course connect it to your computer and switch it on. You may also have to install specific printer driver software for the printer, as instructed, although drivers for some printers are supplied with the system. If you can’t get a driver for your printer from the manufacturer you may need to use Gimp Print (see below).

To make a printer available in Print dialogues you must first enable it in the Printer Setup Utility, formerly known as the Print Center. You can get to this by selecting Edit Printer List in the Printer pop-up menu of any Print dialogue, or by clicking on the Set Up Printers button in the Print & Fax preferences pane. To add a printer, simply click on the Add button and choose the required printer. If it doesn’t appear in the list there’s a problem with your printer driver.

Desktop Printers

A desktop printer icon represents an actual printer: it can be placed anywhere on your computer, including in the Dock, on the desktop or in a Finder window’s sidebar. Double-clicking such an icon puts up a printing queue window, showing how printing is progressing. Files can also be dragged onto the icon to initiate printing: PDF files are printed immediately, whilst other documents cause the appropriate application to be launched and a standard Print dialogue to appear.

To create a desktop printer you must launch the Printer Setup Utility, open the required printer queue window and then select Printers ➡ Create Desktop Printer. Any new desktop printers that you create are normally placed in ~/Library/Printers/, although they can be moved to an alternative location at any time.

PostScript Printers

The images on a computer screen are usually generated by means of mathematical techniques known as vector graphics or object-orientated graphics. The system used for such graphics in Mac OS X is Quartz. During printing, the Quartz descriptions that have been created by the application are rasterised so as to create a bitmap image for the printer.

Quartz is derived from QuickDraw, the drawing system for the Classic Mac OS, and PostScript, which is the most commonly used graphics system for desktop publishing (DTP) applications. The PostScript language, which was devised by Adobe, can describe anything from a single font to a full page of text and graphics. PostScript data can be stored in a PostScript file, in an encapsulated PostScript file (EPSF) or in a Portable Document File (PDF).

A PostScript-based application uses PostScript to create images but puts the results onto the Mac screen using Quartz. A printer that understands PostScript is known as a PostScript printer whilst other printers are known as a QuickDraw printer or non-PostScript printer, despite not having any connection with PostScript or QuickDraw.

PPD Files

The behaviour of a PostScript printer is determined by a matching PostScript Printer Description (PPD) file in the /Library/Printers/ folder that corresponds with your printer. Most PostScript printers won’t work without a suitable PPD, although you may find that a PPD for a similar model may also work with your device.

Each PPD file is actually text file, containing information about the printer in the form of PostScript instructions. Such a file can be viewed and modified using a standard text editor, allowing you can to change the way in which your printer works.

Using a Printer via the Internet

Sometimes you’ll want to take material from the computer that you’re using and print it on a printer that is located somewhere else, such as your main office. To do this via the Internet, using Gimp Print printer drivers and the Common Unix Printing System (CUPS), which are described in more detail below, you should proceed as follows:-

  1. On the machine connected to the printer, open the Sharing preferences pane and enable Printer Sharing.
  2. Download and install Gimp Print (see below), which is at http://gimp-print.sourceforge.net/MacOSX.php3.
  3. Using a Web browser, go to http://127.0.0.1:631, where you can configure CUPS to suit your printer: click on Manage Printers and then select the required printer, which should end up with a URL in the address field of the form http://127.0.0.1:631/printers/printer_name, where printer_name is replaced by the actual name of the printer.
  4. Moving over to the remote machine, open the Printer Setup Utility, hold down Option and click on the Add button, which should reveal another sheet where you should select Advanced in the top pop-up menu. You must then choose Internet Printing Protocol (http) in the Device menu and then enter a name for the printer in the Device Name field, as well as the IP address of the computer connected to the printer. Finally, select the printer model from the Printer Model pop-up menu, click on Add and quit the utility.

  Page Setup and Print Dialogues

Some of the many options that appear in Page Setup and Print dialogues are listed below.

Black & White

Only suitable for printing text that doesn’t have any half-tone details.

Faster Bitmap Printing

This gives faster printing of bitmap graphics. If your document contains imported bitmap images, such as TIFF files or scanned images, it’s best to turn this off.

Font Substitution

This causes Classic Mac OS fonts that were originally in bitmap form, namely New York, Geneva and Monaco, to be replaced by PostScript versions of Times, Helvetica and Courier respectively.

Fractional Character Widths

This option, also called Fractional Widths, can appear in an application’s Preferences window or in a Page Setup or Print dialogue. It isn’t normally enabled, which means that printed characters are spaced at multiples of one pixel (172 inch), often giving a result that doesn’t always look satisfactory. With Fractional Widths enabled the characters are spaced to a greater accuracy, but, depending on the application, can look peculiar on the screen, where the resolution is usually 72 dpi or thereabouts.

Graphics Smoothing

This eliminates harsh jagged edges on bitmap graphics. If your document contains imported bitmap images, such as TIFF files or scanned images, it’s often best to turn this off.

Layout

Lets you print 1, 2 or 4 pages on a single sheet, selected by 1 Up, 2 Up or 4 Up, with optional borders around each page.

Orientation

Determines whether the page is printed as a portrait (the usual way) or as a landscape (sideways).

Page Size

This never seems to be the size you want. In some instances you may have to resort to a larger size than you require with the document carefully designed not to spill over the edges of the paper.

Precision Bit Map

Also known as Bit Map Alignment, this gives a size reduction of 96%, in the process aligning the 72 dots per inch (dpi) resolution of a screen to the 300 dpi resolution of a standard laser printer. This makes one screen pixel equal to exactly four dots on the printer, resulting in a far less jagged printout.

Scaling

Some reductions or enlargements may give lumpy results. Try using 96%, 72%, 48% or 24%.

Tall Adjusted

Only used with the ancient ImageWriter printer, which has a resolution of 80 dpi horizontally and 72 dpi vertically. However, when you select Tall Adjusted it prints at 72 dpi in both directions. Although this option stops circles looking like ovals it increases the document’s width by 11%.

  The Printing Operation

Printing is usually started by choosing File ➡ Print or pressing -P.

Problems and Answers

Printing to Files

Under normal circumstances you’ll send documents to a physical printer so as to get the results on paper. However, you can also ‘print’ documents to other files. In fact, this happens automatically when you select Preview in a Print dialogue: the document is actually converted into a Portable Document Format (PDF) file and then displayed by means of Apple’s Preview application.

You can also ‘print’ to a PDF or PostScript file from the Print dialogue for a PostScript printer. If you don’t have this kind of printer you can create a virtual PostScript printer as follows:-

  1. Launch Printer Setup Utility
  2. Click on Add in Printer List window
  3. In the next sheet select IP Printing and enter localhost in Printer’s Address field
  4. Choose Generic under the Printer Model menu
  5. Click on Add

When printing, you can choose localhost under the Printer menu in the Print dialogue. You can then check Save as File and select the required format, such as PostScript.

Common Unix Printing System (CUPS)

Unix, on which Mac OS X is based, traditionally employs two printing systems: the Berkeley Line Printer Daemon (LPD) and the Line Printer (LP) mechanism devised by AT & T. However, CUPS, as developed by Easy Software Products, is based around Internet Printing Protocol (IPP), although it also includes support for the older LPD system.

CUPS also supports some features of Server Message Block (SMB) or Samba, the standard mechanism used by PCs for printer sharing. It also accommodates AppSocket, sometimes known as JetDirect, and provides a raster image processor (RIP) for non-PostScript printers.

The system employs the following groups of files:-

FileNotes
HTTP Server ConfigurationSimilar to Apache server file
Printer and Class DefinitionLists available printers
MIME Type and Conversion RuleAccommodates different file types
PostScript Printer Description (PPD)For all printers, not just PostScript devices

Its PostScript raster filter is based on the core of GNU Ghostscript 5.50, although CUPS employs its own generic raster printer driver. The basic version of CUPS supports text (standard 8-bit formats and UTF-8), PostScript, PDF and HP-GL/2 files, as well as the following graphics formats:-

BMP, GIF, JPEG, Photo CD (base resolution), PIX, PNG, PNM (PBM, PGM, PPM), SGI, RGB, Sun Raster, TIFF (single page).

Using CUPS

CUPS lets you choose a PPD in the Printer Setup Utility application of Mac OS X and use the matching printer immediately, whether it’s connected directly or via a network. It supports open-source printer drivers, such as Gimp Print, which accommodates numerous printers, including models from Hewlett-Packard, Epson, Canon and Lexmark. Gimp Print can also be used with a PostScript interpreter such as EPS Ghostscript, a special version of GNU Ghostscript 7.05.

You can configure CUPS through a standard Web browser by entering:-

http://127.0.0.1:631

where 631 indicates port 631 of your own machine, as used for the CUPS printer server.

The SMB option can be enabled by entering the following in the Terminal application:-

sudo ln -s usr/bin/smbspool/usr/libexec/cups/backend/smb

pressing Enter and restarting the computer.

Paper Sizes

Metric paper sizes are as follows:-

Metric SizeWidth (mm)Height (mm)Width (in)Height (in)
A0841119133.146.8
A159484123.433.1
A242059416.523.4
A329742011.816.5
A42102978.311.8
A51482105.98.3
A61051484.15.9
A7741052.94.1
B425736410.114.3
B51822577.210.1

whilst others include:-

SizeWidth (mm)Height (mm)Width (in)Height (in)
Folio2103308.313
Foolscap2163308.513
Legal2162568.514
US Letter2162798.511
International Fanfold2103048.312
Ledger2794321117

References

CUPS Web site at www.cups.org.

MacWorld magazine (UK), IDG Communications, 2003-2004

©Ray White 2004.