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PPA Printer-Support RPM Packages for Red Hat Linux and Compatible Distributions

The pnm2ppa project team ppa-rpms@users.sourceforge.net

v0.27, Nov 11, 2000

Information and installation instructions to accompany pnm2ppa packages for Red Hat Linux available at http://sourceforge.net/projects/pnm2ppa (Updated for pnm2ppa-1.04 and later.) See the "Troubleshooting" section at the end of this document for fixes to some reported problems

Overview of HP's PPA DeskJet Printers.

Most of Hewlett-Packard's DeskJet(tm) printers use the PCL3 command language, and are currently supported by Ghostscript drivers. However, a few models, namely

DeskJet 710C Series: HP DeskJet 710C, 712C
DeskJet 720C Series: HP DeskJet 720C, 722C
DeskJet 820C Series: HP DeskJet 820Cxi, 820Cse (discontinued)
DeskJet 1000C Series: HP DeskJet 1000Cxi, 1000Cse (discontinued)

feature "Host-based" printing, and use HP's proprietary PPA (Printer Performance Architecture) protocol, instead of PCL. The two models in each series are physically identical; they just come with different bundled Windows software. The 820C and 1000C series are discontinued at this time (January 2000).

PPA printers rely on software running on the host CPU to carry out the low-level processing of printer output that would be done by hardware in a standard PCL printer. The relation of PPA printers to PCL printers is analogous to the relation between "Winmodems" and true modems.

Unfortunately, HP only supplies Windows software drivers for PPA printers, and have indicated that it is unlikely that they will ever make the proprietary PPA specs public. This is apparently because of concerns that publication of the specs might reveal crucial details of HP's trade secrets about "color science" to competitors. (A secondary issue is that it is apparently possible to physically damage the printer by sending it bad sequences of PPA commands, which is not the case for PCL commands, and it seems that HP do not wish to take any responsibility for such damage by encouraging unofficial PPA programming.)

In fact, the decline in hardware component prices has meant that the anticipated cost-savings through using host-based PPA instead of printer-based PCL are less than expected, and two of the PPA printer series (820C, 1000C) have been phased out, and replaced by similar PCL printers in HP's product line. The 710C and 720C series are still being sold at this time of writing. All other currently-offered DeskJet models appear to be standard PCL3 printers.

Many Linux users may have inadvertently purchased PPA DeskJet models, mistaking them for PCL3 DeskJets, for which independently-produced Linux drivers have long been available. Fortunately, a reverse engineering effort, started in 1998 by Tim Norman, http://www.normsoft.com/ppa and http://pnm2ppa.sourceforge.net, and continued by the pnm2ppa project at http://sourceforge.net/projects/pnm2ppa has managed to produce drivers that provide basic printing functionality for these PPA printers under Linux and other Unices.

The pnm2ppa driver for color printing with PPA printers.

Color printing with PPA printers is supported by the pnm2ppa driver which is the successor to the older black-and-white-only driver pbm2ppa-0.8.6 developed by Tim Norman.

pnm2ppa can translate portable anymap (pnm) format images into a stream of PPA instructions which can be sent to the printer. In the driver name, "pnm" stands for the superset of three image formats: ppm (portable "pixmap" format for color images), pgm (portable "greymap" format for greyscale images), and pbm (portable "bitmap" format for black and white images).

Ghostscript has a number of "output devices" that produce pnm format output from postscript or pdf input. These come in plain (text) and raw (binary) variants. While pnm2ppa can now interpret both plain and raw pnm formats, there is no point in using the inefficient plain formats: always use the "raw" output devices, which are:

ppmraw - raw pixmap format (color images);
pgmraw - raw greymap format (greyscale images);
pbmraw - raw bitmap format (black and white images);
pnmraw - selects between ppm, pgm, and pbm raw formats;
pgnmraw - selects between pgm and pbm raw formats.

The last two output devices are switches that try to analyze the image, and select an appropriate format; however, they are not recommended for routine use, as they may inconsistently choose the format. The ghostscript-5.10 package supplied with Red Hat 6.x distributions provides all these devices; older versions may not. To see the list of available ghostscript output devices, type the command line


gs --help

if the required ppmraw or pbmraw devices are not shown, you will have to upgrade your version of ghostscript.

The data must be streamed directly from ghostscript to pnm2ppa to the (local) printer without being stored in any intermediate file: one ppm-format (color) US Letter size page is represented by 3x5100x6600 Bytes (100MB) in binary format and four times this amount in text format.

An example of a command line for printing a postscript file file.ps using gs (ghostscript) and pnm2ppa is


cat file.ps | gs -q -sDEVICE=ppmraw -r600 -sPAPERSIZE=letter -dNOPAUSE \
 -sOutputFile=- - | pnm2ppa --eco -v 720  -i - -o - | lpr -l

(all on a single line). In this example the paper size is explicitly given to gs as US Letter (8.5"x11") size (letter); pnm2ppa no longer needs to be told what the paper size is, and will read it from the gs output (and check that it is a permitted size for the printer type). The pnm2ppa option --eco specifies "EconoFast" mode, for a lower quality output which uses less ink, and prints faster, and -v 720 specifies the PPA printer as belonging to the DeskJet 720C series.

Obviously, it would be impractical to type such a command each time one wished to print something, so in addition to the pnm2ppa driver itself, an enhanced version of Red Hat's rhs-printfilters RPM package is provided; after this is installed, the PPA printer can be managed like other standard printers with the Red Hat printtool utility. The postscript file can then be printed with the simple command


lpr file.ps

However, if you wish to print to paper sizes supported by ghostscript, but not supported by the Red Hat printtool utility, you can use scripts like the one above. The HP 710C, 720C, and 820C series support paper sizes from 3"x3" to 8.5"x14", while the 1000C supports 4"x6" to 13"x19".

Available RPM packages.

A RPM package for pnm2ppa is part of the Red Hat Linux distribution starting with Red Hat 6.2. You will also find a RPM package for the latest release of pnm2ppa at http://sourceforge.net/projects/pnm2ppa.

The latest version at the time of writing is pnm2ppa-1.04-1.i386.rpm, and is built on Red Hat 6.2. If you are running a different release of Red Hat (or a different Linux distribution) you may need to download and rebuild the source RPM pnm2ppa-1.04-1.src.rpm instead:


rpm --rebuild pnm2ppa-1.04-1.src.rpm

(You must be root to do this, and have the necessary compilers installed; on Red Hat, the rebuilt binary RPM will be created in the directory /usr/src/redhat/RPMS/i386/.)

Red Hat 6.2 and later also includes support for configuring your printer to use pnm2ppa using printtool and rhs-printfilters. If you are using Red Hat 6.1 and earlier,you will need to update the rhs-printfilters that came with the distribution to the rhs-printfilters-1.57-4ppa4.i386.rpm also available at http://sourceforge.net/projects/pnm2ppa. (This is designed to work only with printtool-3.43 and earlier.)

Note: If you are using Red Hat 6.2, you may wish to update the print filter support that it comes with. The pnm2ppa-1.04-1 RPM package supplies the necessary files that you can use. After installing this RPM, see /usr/lib/rhs/rhs-printfilters/README.ppa for details.

Installing the pnm2ppa RPM package and setting up the PPA printer.

To install the RPM package, you must log in as the system administrator, root.

Now begin the installation. First install the pnm2ppa RPM:


rpm -Uvh pnm2ppa-1.04-1.i386.rpm

The pnm2ppa executable gets installed in /usr/bin/.

If you are using a 2.2.x kernel, (e.g. Red Hat 6.x) it will be able to autodetect IEEE-1284 devices like PPA printers, provided they are attached to the parallel port with a bidirectional IEEE-1284 cable. (If your printer works under Windows, you have the correct cable.) (Note that older (2.0.x) kernels do not have this autoprobe facility.) A script detect_ppa is provided by the pnm2ppa RPM: just type


detect_ppa

to confirm that your Printer is found.

It is possible (especially on Red Hat 6.1) that you will have to add a line


alias parport_lowlevel parport_pc

to the file /etc/conf.modules for the printer to be found (this is a parallel port recognition issue, not specific to PPA printers. and a known "gotcha" on Red Hat 6.1). A typical message from the printer, which will be displayed if autodetection is successful, is:


CLASS:PRINTER;
MODEL:DESKJET 820C;
MANUFACTURER:HEWLETT-PACKARD;
DESCRIPTION:Hewlett-Packard DeskJet 820C;
COMMAND SET:SCP,VLINK;

A list of PPA printers found, and the parallel ports to which they are attached, will also be shown.

At this point it is useful to test that your printer is working, by printing a test page using the supplied script test_ppa which the RPM has installed. You will need to know your printer model (710, 712, 720, 722, 820, 1000), your paper size (letter, legal, a4) and the printer port the printer is attached to. If it is attached to the primary parallel port, this is /dev/lp1 under older 2.0.x kernels, and (usually) /dev/lp0 under newer 2.2.x kernels, as in Red Hat 6.x. Type


test_ppa

and give the details about printer model. papersize, and port number when prompted. You will then be asked whether to print a test page, an offset calibration page, or an alignment calibration page, etc.

Tip: The test_ppa script does not use the print filters that will be installed by the rhs-printfilters RPM, so it is useful when troubleshooting, for testing if any printing problems are associated with the basic printer installation, or with the configuration of the print filters.

Installing the PPA-enhanced rhs-printfilters RPM package (if needed).

This step is NOT needed on Red Hat 6.2 or later.

The rhs-printfilters rpm distributed with Red Hat 6.1 does not support pnm2ppa, If you use an older distribution, you will first have to replace their rhs-printfilters RPM with the PPA-enhanced version from the pnm2ppa project.

Once you have confirmed you have a working printer, install the RPM rhs-printfilters-1.57-4ppa4.i386.rpm


rpm -Uvh rhs-printfilters-1.57-4ppa4.i386.rpm

Configuring the print filters with printtool.

Now start the "Red Hat Linux Print System Manager" (as root) to configure the printer, either by clicking on the printer icon in Red Hat's "control-panel", or just typing


printtool

In the Print System Manager window, click on Add, then in the "Add a Printer Entry", select Local Printer, and click Ok. Hopefully, the port on which the printer is attached will be listed as "Detected" (if not, fix the problem before continuing, perhaps by adding the line "alias parport_lowlevel parport_pc" to /etc/conf.modules), as mentioned above. You will now have to "edit the local printer entry" for the PPA printer. Click on Select to chose the "Input filter". The Configure Filter screen will open. Among the many printer entries in the list "Printer Type", you should find three entries

HP DeskJet 1000 series (PPA) (for 1000Cse, 1000Cxi models)
HP DeskJet 710/720 series (PPA) (for 710C, 712C, 720C, 722C models)
HP DeskJet 820 series (PPA) (for 820Cse, 820Cxi models)
- If these entries do not show up, it may be because the older rhs-printfilters package that you updated did not allow the printer database /usr/lib/rhs/rhs-printfilters/printerdb to be replaced. Try deleting or renaming the printerdb file, and then reinstall the PPA-enhanced rhs-printfilters RPM using "rpm --force -Uvh rhs-printfilters*"

Select the appropriate entry for your printer model. You will then be presented with various options:

The Driver Description box contains information about the driver (you may have to use the scrollbar at the right of the box to read it all).
The resolution box shows a single resolution (600x600). There are no other choices.
The Paper Size box allows various choices (only letter, legal, and a4 seem correspond to native paper sizes printed by the Red Hat print filters; the other choices, (a3, ledger, ...) appear to get resized by the print filters to print on US Letter size paper (?) ). (Other paper sizes cannot be selected this way, but you can print to any papersize, if it supported by both ghostscript and the printer, using a script, as described above, that bypasses the RedHat printfilters.)
The Color Depth/ Uniprint Mode box allows various selections of color and print quality (These are achieved by using various combinations of the pnm2ppa options --eco (EconoFast mode), -p (disable black ink cartridge) and --bw (black and white printing only), without direct intervention by the user.) The choices (in the most recent printerdb database) are:
- Black and White, econofast mode (--bw --eco)
- Black and White, normal quality (--bw)
- Color, econofast mode (--eco --fd)
- Color, normal quality (--eco)
- Color, high quality
- Color, normal quality, black ink disabled (-p --eco)
- Color, high quality, black ink disabled (-p --uni)
(These are the choices that will be presented by "official" rhs-printfilters-1.72; if you installed a pnm2ppa RPM package from the SourceForge pnm2ppa site, you may have a file /usr/lib/rhs/rhs-printfilters/README.ppa explaining how to modify earlier versions of rhs-printfilters to show these updated choices.) You may also see a choice to use the older "Legacy" driver pbm2ppa (black and white only); this is is stable but unmaintained; it may still be a useful alternative to pnm2ppa on older, slower systems with less available memory.
The three Printing options are not relevant here, and should not be selected. They are for direct printing of text (ascii) to non-postscript printers, but since the only way of printing text files with pnm2ppa is by first converting them to postscript(tm), this is not possible on the PPA printer.
- It is important that the choice "Fast text printing (non-PS printers only)" is NOT selected, so that the print filters will convert text files to postscript before printing.
The Margins entries control the margins used when printing text files (these are instructions to the text-to-postscript conversion process).
The Extra GS options box is not only a place for adding options for ghostscript, but also for the PPA drivers. Leave this box empty unless you know what you are doing. As explained in the text in the Driver Description box (you did read it, didn't you ?), the entry should be in the format:
gs_options PPA ppa_options
Anything before the "PPA" is interpreted as a gs option, anything after it is interpreted as a ppa option. You can learn about pnm2ppa options by typing either "man pnm2ppa" or "pnm2ppa --help" at a command line (hopefully, these two sources of information will be consistent with each other!);

When you have made your choices, click on Ok to save your selections and close the "Configure Filter" screen, and then click on OK to close the "Edit Local Printer Entry" screen.

You are now back in the "Red Hat Print System Manager" screen; highlight the printer you just configured, and, in the Tests menu, choose Print Postscript test page to print a test page using the Red Hat print filters. If this printed correctly, your print system is set up to use the PPA printer, just like any of the other printers that the Red Hat print filters support.

Configuring pnm2ppa.conf and calibrating the printer.

A number of printer parameters are set to reasonable default values for each of the printer models, but you may wish to "fine tune" or calibrate your printer. The default values can be overridden by entries in the configuration files, which by default are /etc/pnm2ppa.conf and /etc/pbm2ppa.conf. At 600dpi, one pixel is 1/600 inch.

The user-adjustable parameters are:

verbose 1 and silent 1. These control messages about progress and errors from pnm2ppa. By default, messages are sent to the system log /var/log/messages. The verbose 1 keyword send copies to stderr, the standard error stream to the terminal. The silent 1 keyword silences the stream of messages to the system log.
- The system log messages may be silenced in the default configuration file; switch off "silent" mode with "silent 0" for debugging printer problems (or use verbose mode).
The version keyword can be used to specify the printer model as 710, 712, 720, 722, 820, or 1000. It is not needed if you use the RedHat printool to configure the printer.
xoffset and yoffset: the x-offset and y-offset (in pixels) of the printed image on the page, which should be chosen so the image is correctly centered on the paper. (These can also be set with the -x <xoff> and -y <yoff> options.) See CALIBRATION.html (or CALIBRATION.txt) for more information.
topmargin, bottommargin, leftmargin, rightmargin: the four margins, which define the distances (in pixels) from the edges of the paper to the printed region; parts of the image that are outside these margins will not be printed. (These can also be set with the -t <top margin> , -b <bottom margin> , -l <left margin> , and -r <right margin> options.)
ColOffsX and ColOffsY: the x-offset and y-offset (in pixels) between the color image produced by the color ink printer head, and that produced by the black ink printer head. These should be recalibrated each time an ink cartridge is replaced. See CALIBRATION.html (or CALIBRATION.txt) for more information.
blackshear and colorshear: these are x offsets between right-to-left and left-to-right sweeps of the print head, one for the black printing and one for the color printing. These provide sideways offsets (in pixels) of the right-to-left sweeps, that can be used to correct "shearing" when printing in modes that use bidirectional print head sweeps.
unimode 1 will make unidirectional print sweeps (left-to-right) the default, instead of bidirectional sweeps. The --uni and --bi options can control how a particular print run is printed. Unidirectional printing is only useful (it is slower) if there are issues of "shearing" in high quality image printing.
blackness : this takes values 0,1,2,3 or 4 drops of black ink per pixel, and controls black ink density in black-and-white and "text-like" black regions in color printing. At present, this has no effect on printing with the black ink cartridge disabled, or on black regions identified as "image-like". (This can also be set with the -B <n> option, where n is the number of drops.)
GammaR, GammaG, and GammaB: the are the three "gamma" parameters that define the standard color correction curves for red, green, and blue. Changing these will affect how colors appear (decreasing any Gamma enhaces the corresponding color). The Gamma values are specified as decimal numbers, with Gamma = 1.0 corresponding to no color correction.
Gamma values can also be specified using integer numbers RedGammaIdx, GreenGammaIdx, BlueGammaIdx; These are determined by a procedure discussed in COLOR.html or COLOR.txt, which involves printing a test page. The papersize keyword specifies the paper size used for this testpage, because it is produced by pnm2ppa without the input that usually specifies the page size.
The keywords black_ink 0, color_ink 0, cyan_ink 0, magenta_ink 0, and yellow_ink 0 can be used to switch of the various inks; this can be useful in troubleshooting and debugging pnm2ppa.

Use test_ppa to print various test pages or calibration patterns to adjust the offsets.

If you wish to specify these parameters using the command-line options described above, some of them can be entered in the "extra GS options" box using the Print System Manager (printtool), as described above.

Utility programs for the printer.

HP's Windows software provides a utility program that sends PPA commands to tell the printer to perform taks like cleaning the printheads, etc. The codes for some of these functions have already been reverse engineered. There are proposals to add support for PPA printers to the PUP (Printer Utility Program) utility, which is also a project at http://www.sourceforge.net. However, as of the time of writing, no PUP support for PPA printers is available (volunteers, anyone?).

Troubleshooting

The first thing to do is to look at the messages from pnm2ppa in the system log to see what is happening, whether pnm2ppa actually received any input, and if it was valid. (You may need to enable system log messages in /etc/pnm2ppa.conf, see above.) Maybe ghostscript failed to convert your postscript file into PNM format: this is not a pnm2ppa problem! Here are suggestions for dealing with problems that you may encounter.

Printing fails in the middle of a print run, perhaps when a figure embedded in the document is printing (in the latest pnm2ppa versions, printing finishes normally, but an incomplete document is printed). The system log reports that read_line could not read the image, and found EOF (end-of-file). This probably means that ghostscript's "ppmraw" or "pgmraw" output device failed for some reason, usually leaving a core dump, without completing the translation of the postscript to a pnm format. (This has been seen to happen in ghostscript 5.10 ; upgrading to ghostscript 5.50 solved the problem.) If you cannot upgrade, try printing the document in black-and-white using the ghostscript "pbmraw" output device.
The test_ppa script works, but you can't get printtool to make the printfilters work. You installed pnm2ppa-1.0 and the PPA-enhanced rhs-printfilters (earlier than v. 1.61) from the pnm2ppa SourceForge page. You are using printtool v. 3.43 or earlier and are probably a Mandrake user. Solution: (a) use printtool to uninstall the PPA printer; (b) delete (or rename) the printer database /usr/lib/rhs/rhs-printfilters/printerdb, and reinstall the rhs-printfilters RPM using the "rpm --force ... " option; (c) use printtool to add the PPA printer again. (Your previously-installed rhs-printfilters may have resisted replacement of its printerdb).
You upgraded your RedHat (or compatible) Linux distribution and your printfilters no longer work. You used to use a PPA-enhanced rhs-printfilters from the pnm2ppa SourceForge site. You upgraded your distribution to one using printtool v 3.44 or later (e.g. RedHat 6.2). Solution: Make sure that rhs-printfilters has been updated to a version 1.61 or greater that came with your upgraded distribution. Use printtool to delete, and then add the PPA printer This will create a new printer configuration compatible with your upgraded distribution.
You printed an image file using a "high quality" printer setting, but it has visible horizontal lines on it and printing under Windows(tm) 9x doesn't show this effect (except in "economode"). These are probably "swath boundaries", showing the junction between different sweeps of the print head. Solution: using unidirectional printing (PPA option --uni, or unimode 1 in /etc/pnm2ppa.conf) helps a little, but this problem requires an extensive rewrite of part of pnm2ppa (cutswath.c) for a satisfactory solution. (Volunteers welcome - see the TODO file in the pnm2ppa docs (/usr/doc/pnm2ppa*/TODO)!)
"Flashing light syndrome ". Your printer usually works, but you have found that some particular documents cause the printer to fail, and the lights on its panel start flashing rapidly in sequence. Solution, turn the printer off and back on again. This is not supposed to happen any more; if it happens reproducibly, contact the pnm2ppa developers, and offer to make the offending file available for testing and diagnosis of this problem. (Don't sent it to the Mailing List unless requested). Bug reports can be filed at the SourceForge pnm2ppa site.
You wish to print on envelopes or other non-standard media not supported by the print filters? Solution: if you can get Ghostscript (gs) to produce the correct image, and the paper size is in the range allowed by your printer, you should be able to do this with a script that bypasses the print filters, as described earlier in this document.
Colors look wrong, or do not match what the Windows(tm) 9x driver produces. Solution: check that your color ink cartridge is not running out of some ink color; if not, (a) adjust the "gamma" entries in /etc/pnm2ppa,conf, or (b) install a customized color calibration file /etc/pnm2ppa.gamma. See the file COLOR.html (or COLOR.txt) for more information.

Contacting the pnm2ppa project.

Send comments or corrections (about this document or the RPMS) to: ppa-rpms@users.sourceforge.net

There are three mailing lists, ppa.announce (announcements), ppa.users (users helping users) and ppa.devel (developers). You can subscribe to them, or browse their archives, at http://pnm2ppa.sourceforge.net/maillist.htm.

To contact the developers, subscribe to ppa.devel and post a message.

There are Public Forums for posting questions and comments at http://sourceforge.net/projects/pnm2ppa (but whether you get any help from these, depends on whether anyone is reading them).

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