GS-PCL3(1) GS-PCL3(1)
NAME
pcl3 -- ghostscript device driver for printers understanding PCL 3+
SYNOPSIS
gs -sDEVICE=pcl3 [gs_option | -dBlackLevels=integer |
-dCMYLevels=integer | -sColorModel=model | -sColourModel=model |
-dCompressionMethod=method | -dConfigureEveryPage | -dCUPSAccounting
| -dCUPSMessages | -dDepletion=depletion | -dDryTime=seconds | -sDu-
plexCapability=capability | -sIntensityRendering=method |
-dLeadingEdge=edge | -dManualFeed | -sMediaConfigurationFile=pathname
| -dMediaPosition=position | -sMedium=medium | -dOnlyCRD | -sPage-
CountFile=pathname | -sPCLInit1=string | -sPCLInit2=string |
-sPJLJob=jobname | -sPJLLanguage=language | -sPrintQuality=quality |
-dRasterGraphicsQuality=quality | -dSendBlackLast | -dSendNULs=number
| -dShingling=shingling | -sSubdevice=subdevice | -dTumble | -dUse-
Card=value ] ... [file ...]
DESCRIPTION
Supported Printers
The ghostscript device driver pcl3 (formerly called hpdj) is a
ghostscript backend for printers understanding Hewlett-Packard's
Printer Command Language, level 3+ ("PCL 3+", also called "PCL 3
Plus"). The driver is intended to support in particular the following
printer models:
HP DeskJet
HP DeskJet Plus
HP DeskJet Portable
HP DeskJet 310
HP DeskJet 320
HP DeskJet 340
HP DeskJet 400
HP DeskJet 500
HP DeskJet 500C
HP DeskJet 510
HP DeskJet 520
HP DeskJet 540
HP DeskJet 550C
HP DeskJet 560C
HP DeskJet 600
HP DeskJet 660C
HP DeskJet 670C
HP DeskJet 680C
HP DeskJet 690C
HP DeskJet 850C
HP DeskJet 855C
HP DeskJet 870C
HP DeskJet 890C
HP DeskJet 1120C
The PCL dialect called "PCL Level 3 enhanced" is apparently a not
entirely compatible modification of PCL 3+. This driver should basi-
cally work with such printers but you must be more careful which
options you select and you might not be able to exploit all your
printer's capabilities.
The driver does not support printers understanding only Hewlett-
Packard's PPA (Printing Performance Architecture) commands. If a
printer's documentation does not say anything about its printer command
language and you find a statement like "... is designed for Microsoft
Windows" or "DOS support through Windows only", the printer is almost
certainly a PPA printer and hence is intended exclusively for systems
running Microsoft Windows. (These printers are also erroneously known
as "GDI printers" because they are intended to be accessed through a
manufacturer-supplied driver via Windows' GDI interface.) There exist
ways of using a PPA printer with ghostscript, but not through pcl3.
Different printer models usually implement model-specific subsets of
all PCL-3+ commands or arguments to commands. You must therefore tell
the driver by means of the Subdevice option for which model the gener-
ated PCL code is intended. The model-dependent difference in the gen-
erated code is not great. Apart from media specifications, resolutions
and colour capabilities, one can consider three groups of models which
are treated with significant differences:
Group 1 DeskJet, DeskJet Plus, DeskJet 500
Group 2 DeskJet Portable, DeskJets 3xx, 400, 5xx except 500
and 540,
Group 3 DeskJets 540, 6xx, 8xx and 1120C.
The first two groups I call the "old Deskjets", the third group con-
sists of "new DeskJets". If you have a PCL-3 printer not appearing in
the list above, the likelihood is still good that it will accept the
files generated by pcl3. You can specify one of the supported subde-
vices in these cases (it is sufficient to try one each from the groups
just mentioned), or use the special subdevice names unspecold or unspec
which are treated like members of the second and the third group above,
respectively, with all subdevice-dependent checks having been turned
off.
The list of printer models for which this driver is currently known to
work is:
HP 2000C
HP 2500CM
HP DeskJet 697C
HP DeskJet 850C
HP DeskJet 970C
HP DeskJet 1100C
Xerox DocuPrint M750
Details can be found in the file reports.txt in the pcl3 distribution;
its latest version is available via pcl3's home page (link to URL
http://home.t-online.de/home/Martin.Lottermoser/pcl3.html) . If you
wish to report on the hardware compatibility for a particular printer
model, please read the file how-to-report.txt.
Omitting models already mentioned, previous (hpdj) versions of this
driver were reported to work with the following printers:
HP DeskJet 340
HP DeskJet 400 (tested for Gray only)
HP DeskJet 420
HP DeskJet 500
HP DeskJet 500C (tested for Gray only)
HP DeskJet 520
HP DeskJet 540
HP DeskJet 560C
HP DeskJet 600
HP DeskJet 610C
HP DeskJet 612C
HP DeskJet 640C
HP DeskJet 660C/660Cse
HP DeskJet 670C
HP DeskJet 672C
HP DeskJet 680C
HP DeskJet 690C
HP DeskJet 690C+
HP DeskJet 693C
HP DeskJet 694C
HP DeskJet 832C
HP DeskJet 855C
HP DeskJet 870Cse/870Cxi
HP DeskJet 880C
HP DeskJet 890C
HP DeskJet 895Cse/895Cxi
HP DeskJet 932C
HP DeskJet 1120C
HP OfficeJet 350
HP OfficeJet 590
HP OfficeJet 600
HP OfficeJet 625
HP OfficeJet G55
HP OfficeJet T45
Lexmark 3000 Color Jetprinter
Olivetti JP792 (see the option SendBlackLast)
Most of the people who sent me reports did not state to which extent
hpdj worked for their printer model.
Colour Models
Ignoring photo cartridges which are not supported by pcl3, DeskJet
printers can be classified in four categories:
o The printer has only a black ink cartridge.
o The printer can print with either a black or a cyan/magenta/yel-
low (CMY) cartridge.
o The printer holds a CMY and a black cartridge simultaneously, but
the two groups of inks are chemically incompatible and should not
be overlayed. (Don't worry: the printer is not going to explode
if they do. You merely get poorer results because the black ink
will spread further than it should. This is called "ink bleed-
ing".)
o The printer holds a CMY and a black cartridge simultaneously and
the inks can be mixed. (Newer HP DeskJets use such bleed-proof
inks.)
This leads to four (process) colour models for the driver:
Gray Print in black only.
CMY Print with cyan, magenta and yellow. In this mode,
"composite black" consisting of all three inks is used
to stand in for true black.
CMY+K Print with all four inks, but never mix black with one
of the others.
CMYK Print with all four inks.
As a printer with both, a black and a CMY cartridge, can usually also
print, e.g., with black only, the printer's "cartridge state" merely
identifies one of these models as the maximal one. Depending on the
category of the printer, the driver will therefore accept one or more
models. The possibilities are:
DeskJet Model Colour Models
------------------------------------------------------
DeskJet, DeskJet Plus, DeskJet Gray
Portable, 500, 510, 520
310, 320, 340, 400, 500C, 540, 600 Gray, CMY
550C, 560C Gray, CMY, CMY+K
660C, 670C, 680C, 690C, 850C, all
855C, 870C, 890C, 1120C
The subdevices unspecold and unspec also permit all colour models. A
printer capable only of CMY might accept CMY+K or CMYK data, remapping
them to CMY, and a printer capable of CMY+K might remap CMY data to
CMY+K.
The colour model CMY+K is not useful if you have a CMYK printer. In
contrast, if you have a CMY+K or CMYK printer and the two cartridges
support different resolutions, the colour models Gray or CMY become
interesting as well. In most of these cases the black cartridge can
print at a higher resolution than the CMY cartridge, although the con-
verse does also occur. In addition, ghostscript is generally fastest
for Gray.
PCL 3+ also supports the colour model RGB although Hewlett-Packard dis-
courages its use. For this model the printer internally converts the
RGB data it receives into CMY data for printing. Note that not every-
thing which can be demanded when using a CMY palette in PCL 3+ is also
permitted when using RGB. Because of its limited usefulness, pcl3
accepts the colour model RGB only for the subdevices unspecold and
unspec.
Media Sizes and Orientations
A PostScript document describes its visible content with respect to a
coordinate system called default user space. Almost all PostScript
devices are page devices which paint only a restricted rectangular area
in default user space. Part of the state of a page device is therefore
the current page size, two numbers specifying the width and height of
the sheet to be printed on. These values must be interpreted from
default user space, hence the page size not only describes the "sheet
size" (extension irrespective of orientation) but also the orientation
between page contents and sheet (portrait if width <= height, landscape
otherwise). The page size is requested by the user or the document,
and it is one of the jobs of the device to satisfy this request.
Ghostscript looks at several sources to determine the page size:
o the default size configured for gs (usually US Letter or ISO A4
in portrait orientation),
o the value given to the option PAPERSIZE in the invocation,
o the size requested by the document, unless you specify -dFIXEDME-
DIA.
The last applicable item in this list overrides the others, hence the
current page size can change at runtime.
The pcl3 driver splits the page size into sheet size and page orienta-
tion and passes the sheet size to the printer. This works only if the
printer accepts this size (accepted sizes are listed in your printer's
manual). For the explicitly supported printers, the driver knows which
sizes are accepted and will refuse to print if an unsupported one is
requested. (If you suspect that pcl3 is in error concerning what is
supported, check the list of supported sizes in the PPD file for the
subdevice you are using.) Group-3 printers also accept a custom page
size command which permits printing on arbitrarily-sized media but only
within certain limits which are also known to the driver. Unlike the
sheet size the page orientation is irrelevant for deciding whether a
particular page size is supported or not. The driver will adapt itself
as required by the PostScript language and rotate the output if neces-
sary. (I know of only one other ghostscript driver capable of this.)
In setting up the PostScript default user space, pcl3 does not treat
envelope sizes differently from other sizes.
The subdevice unspecold accepts all sizes supported by the HP DeskJet
560C, unspec supports all discrete sizes known to the HP DeskJets
850C/855C/870C/890C and treats in addition every other size request as
a custom page size without imposing any limits. If using any of these
two subdevices you should change the list of supported sizes to fit
your printer's capabilities; see the CONFIGURATION section below for
details.
In order for a document to be printed correctly a sheet of appropriate
size must be provided and the driver must know what its orientation
with respect to the printing mechanism is. The latter is usually spec-
ified by reference to the feeding direction as "short edge first" or
"long edge first". Don't confuse this kind of orientation with the
portrait/landscape orientation: the former ("sheet orientation") refers
to the orientation of the sheet with respect to the feeding direction,
the latter ("page orientation") describes the orientation of the sheet
with respect to the page contents (default user space). These orienta-
tions are logically independent: people inserting paper into the
printer need to know about the first, people composing documents only
care about the latter.
Because pcl3 has no information about the actual dimension or orienta-
tion of the medium in the input tray, you must ensure yourself that
this is appropriate. By default, the driver assumes the dimension to
be that requested via the page size, but you can override this assump-
tion with an InputAttributes definition (see the Media Sources and Des-
tinations subsection in the CONFIGURATION section below).
There is no command in PCL 3+ to tell the printer about the sheet's
orientation in the input tray, therefore it cannot be chosen and the
manufacturer must prescribe it. I am not aware of any precise and com-
plete statement from Hewlett-Packard about what is required in this
respect, hence you should check your printer's manual whether the
assumptions made by pcl3 are correct or not: the driver assumes that
media are always fed short edge first except when using the subdevices
hpdj, hpdjplus, hpdj400, hpdj500 or hpdj500c for printing on envelope
sizes (US no. 10 and ISO DL). In these cases you should insert the
medium long edge first. If you find that pcl3's default behaviour is
incorrect, you can override it with the option LeadingEdge or a media
configuration file (see the CONFIGURATION section below).
Print Quality and Media Properties
With the introduction of the DeskJet 540, HP added two new PCL commands
to the language: "Print Quality" and "Media Type". For older DeskJets
(groups 1 and 2), similar effects can be achieved by specifying some
technical aspects of the printing process in detail.
You can use the PrintQuality and Medium options to adapt the driver to
the desired output quality and those properties of the medium it must
know about, independent of which kind of subdevice you select. If it
corresponds to a printer understanding the new commands, the option
values are passed through to the printer, otherwise these specifica-
tions are mapped to the older Depletion, Shingling, and Raster Graphics
Quality commands based on recommendations from HP. If you are not sat-
isfied with the result in the latter case, use the options Depletion,
Shingling and RasterGraphicsQuality to explicitly set these values.
Diagnostic Messages
Error messages issued by this driver start with "? component:" and
warnings with "?-W component:". The component can be eprn, pcl3, or
pclgen, corresponding to the driver's three internal layers: the eprn
device extends ghostscript without knowing PCL, pclgen is a module gen-
erating PCL without being aware of ghostscript, and pcl3 is the driver
proper connecting the other two layers.
All these messages are written on the standard error stream.
OPTIONS
When specifying options for gs you should keep in mind that case is
significant, that some options must be passed as strings (-s) and oth-
ers as general tokens (-d), and that gs effectively ignores every
option it does not recognize. Hence some care in spelling parameter
names is necessary.
If you are confused by the large number of options, don't worry. Just
ignore those you don't understand and concentrate first on the follow-
ing ones, given here in the order of their importance: -sDEVICE, -sSub-
device, -sColourModel, -r, -sPrintQuality, and -sMedium. You should
also check whether there is an entry in the reports.txt file in the
pcl3 distribution listing working option combinations for your printer.
Standard Options
When calling gs with the pcl3 driver you can specify any option defined
for ghostscript's prn (printer) device although some have particular
meanings or restrictions. This includes all device-independent options
described in gs(1). You should also look into ghostscript's extended
documentation (file <Use.h> (link to URL Use.htm) and the section
Device parameters (link to URL Language.htm#Device_parameters) in Lan-
<guage.h>).
-sDEVICE=pcl3
This specification selects the pcl3 driver, but this is not
the only way to select it with this option. See the descrip-
tion of the Subdevice option below for other possibilities.
-dDuplex[=boolean] or -dDuplex=null
This parameter requests duplex printing and can be set to
true only for unspec and unspecold, and when the DuplexCapa-
bility value is not none. The default is null which for this
driver means that the printer's default setting will be used.
If your printer does not support duplex printing you can
achieve the same effect manually by printing the odd and even
pages separately (use a command like psselect(1) from the
psutils package for extracting these parts) and reinserting
the paper in between.
-r resolution
This option specifies the resolution in pixels per inch (ppi;
sometimes also called dots per inch, dpi). The driver checks
whether the subdevice selected accepts the given resolution
unless the subdevice is unspecold or unspec. Resolutions
supported by at least some of the other subdevices for some
of the colour models are 75, 100, 150, 300, 600x300 and 600
ppi. Consult the PPD files in the pcl3 distribution if you
want to know the details. The default resolution for pcl3 is
300 ppi.
At least the highest possible value should be listed in your
printer's manual, but some care is necessary in the interpre-
tation: the value given to pcl3 must be a resolution sup-
ported by the printer's hardware for all the colorants in the
process colour model simultaneously and when operating in
raster graphics mode. You should also keep in mind that if
your printer has two cartridges they might support different
sets of resolutions, i.e., which resolution you can choose
might depend on the colour model. It is also possible that
the print quality has to be considered as well. If you are
in doubt and have access to a manufacturer-endorsed driver
for your printer, use pcl3opts to find out about the settings
used by that driver.
At least some of the series-500 DeskJets claim to permit a
resolution of 600 x 300 ppi. However, although these models
have a 600 dpi addressable horizontal resolution grid they do
not permit neighbouring pixels to be activated (and the dots
printed still have a diameter of about 1/300 in). The raster
data generated by gs does not obey this restriction. In
addition, it is possible that the higher resolution is anyway
only supported for the printer's builtin fonts and not for
general raster data.
Concerning the DeskJet 870C, my impression is that although
some HP documents and drivers use expressions like "600x300
dpi C-REt color" for this printer, the model does not really
support a resolution of 600 x 300 ppi. First, it does not
accept pcl3's output with this resolution, and second, if one
inspects the best output of HP's Windows driver for this
printer with pcl3opts, one finds that the file uses a "mixed
resolution", i.e., 600 ppi for black and 300 ppi for CMY.
This is not supported by pcl3.
Pcl3-Specific Options
-dBlackLevels=levels and -dCMYLevels=levels
These options set the number of intensity levels per pixel
and colorant to use when printing with black or CMY inks,
respectively, and must be consistent with the colour model.
They permit access to the printer's Colour Resolution
Enhancement technology (C-REt) feature. The defaults are 0
or 2, depending on the colour model chosen. Other values are
only accepted for the subdevices hpdj8nnc, hpdj1120c and
unspec, and when not using the colour model RGB.
The subdevice unspec accepts any non-negative number of lev-
els except 1 up to 256. The subdevices hpdj8nnc and
hpdj1120c accept the levels 0, 2, 3 and 4 with the following
restrictions if any of the levels is larger than 2 (these
restrictions have been determined experimentally with a
DeskJet 850C and are not based on HP documentation):
o You can't use this feature with draft quality.
o You can't use a colour model of CMY.
o You must use a resolution of 300 ppi.
o You must use 4 levels for black.
When using the subdevice unspec you should expect the printer
to similarly limit the possibilities. In particular you must
expect the permitted number of levels to depend on colour
model, resolution and print quality. So far I have not heard
of a PCL-3+ printer supporting more than four intensity lev-
els per colorant.
-sColorModel=model or -sColourModel=model
This selects the colour model to be used by the driver: Gray,
RGB, CMY, CMY+K or CMYK. The default is Gray. Which colour
models are accepted depends on the subdevice, see Colour Mod-
els in the section DESCRIPTION above.
A value of CMY for this option also sets BlackLevels to zero,
and if CMYLevels is zero when you demand any of CMY, CMY+K or
CMYK, it is set to two. For RGB, effectively the same hap-
pens as for CMY. For all other situations you must ensure
yourself that colour model and intensity levels are consis-
tent or pcl3 will complain. This rule implies that you can
ignore the level options unless you want to use a non-default
number of levels.
The PostScript page device dictionary entry ProcessColorModel
will not be correct for a colour model of CMY or CMY+K.
(Ghostscript returns the native colour space in this parame-
ter, not the process colour model.)
-dCompressionMethod=method
PCL interpreters understand several compression methods for
raster graphics data in order to speed up host-printer commu-
nication. The possible choices are:
0 Unencoded, non-compressed
1 Runlength encoding
2 Tagged Image File Format
(TIFF) revision 4.0 "Pack-
bits" encoding
3 Delta Row Compression
9 Compressed Replacement
Delta Row Encoding
The default method is 9 except for the subdevices hpdj, hpdj-
plus, and hpdj500 where it is 3 (these printers do not sup-
port method 9), and for the subdevices unspec and unspecold
where it is 2 (this seems to give the best combination of
portability and compression). Requesting method 3 actually
leads to a combination of methods 2 and 3. The driver may
temporarily choose method 0 if a compressed data sequence
would be longer than its uncompressed version.
Compression rates can vary drastically, depending on the
structure of the input. However, although the absolute val-
ues change, the relative order of efficiency between the
methods is usually the order of increasing method. In short:
use method 9 if it is supported.
-dConfigureEveryPage[=boolean]
This parameter, if set to true, will force the printer to be
reconfigured for every page. The option is superfluous for
printers which are truly PCL-3-conforming.
Use this parameter if you discover that you can print single-
page documents without problems but that the printer does not
accept multi-page files. At present, the only printer I know
of for which such a reconfiguration is needed is the Xerox
DocuPrint M750.
-dCUPSAccounting[=boolean]
You will usually specify this parameter when using pcl3 as
the final component in a CUPS (Common UNIX Printing System)
driver. It will lead to appropriate page accounting messages
on standard error. The default for this parameter is false.
If you have set this parameter to true you can't set it back
to false. The driver will generate a warning if this is
attempted.
When using pcl3 within CUPS you will normally set both, CUP-
SAccounting and CUPSMessages. There exist, however, CUPS
configurations where page accounting messages should be gen-
erated by a command further down the print pipeline than pcl3
(e.g., by a CUPS backend capable of processing PJL Page Sta-
tus messages and driving a printer which sends them). In
these cases you should not specify -dCUPSAccounting.
-dCUPSMessages[=boolean]
Specify this parameter when using pcl3 as a component in a
CUPS (Common UNIX Printing System) driver. It will modify
the format of error messages and warnings as expected by
CUPS. The default for this parameter is false.
-dDepletion=depletion
This option is only available for old DeskJets (including
unspecold) and when printing in colour. The integer deple-
tion controls an algorithm for removing certain pixels from
the image; this leads to less ink being applied to the
medium. The possible values for depletion are:
1 No depletion
2 25%
3 50%
4 25% with gamma correction
5 50% with gamma correction
The default value is derived from Medium and PrintQuality.
The values 4 and 5 are not understood by the DeskJet 500C,
but even for the other printers these values are not useful
because PostScript permits finer control for gamma correction
through transfer functions (see the subsection Transfer Func-
tions in the next section).
-dDryTime=delay
With the exception of the DeskJets 500 and 500C, series-500
DeskJet printers can be told to guarantee a minimum drying
time of delay seconds before the next page of the same print
job is dropped on a newly printed page. (This interval can
be terminated by pressing the Load/Eject button.) The
printer will choose default values depending on the current
print quality, hence it is normally not necessary to specify
this option and the feature is even considered obsolete for
post-series-500 DeskJets although it is still supported by
some of them.
Permissible values for delay are null and integers in the
range 0 to 1200, where null instructs pcl3 not to send a cor-
responding command, 0 establishes default values for the cur-
rent print quality, and all other values explicitly request
the duration in seconds. The default is null.
-sDuplexCapability=capability
Looking at the final result (sheet printed), there are two
kinds of duplex printing identified by the two possible val-
ues for the option Tumble. Not all printers capable of
duplex printing, however, provide the hardware support neces-
sary for both, hence the driver must be told what the printer
offers in order to be able to compensate for the missing
functionality. The parameter capability can be any of the
following:
none no duplex capability
sameLeadingEdge second pass of sheet
occurs with the same lead-
ing edge
oppositeLeadingEdge second pass of sheet
occurs with the opposite
leading edge
both second pass of sheet can
occur with either edge
This option can only be specified for unspecold and unspec.
The default value is none.
The correct setting for the HP DeskJet 970C is opposite-
LeadingEdge, but the printer permits access to its duplex
functionality only if you specify in addition -sPJLLan-
guage=PCL3GUI -dOnlyCRD. (Many thanks to Dawei W. Dong for
an extensive series of experiments.)
If a printer does not offer hardware support for both orien-
tations, the document to be printed must execute showpage
after a possible page-level restore and not before, otherwise
the driver will not be able to compensate for the missing
functionality and only one of the two Tumble values will
work. All DSC-3.0-conforming PostScript files have the
required property.
-sIntensityRendering=method
Most printers, including every PCL-3+ printer I know of, can
render only a small number of intensities per pixel and col-
orant. In the most frequent case, merely two levels are pos-
sible. As this is usually not sufficient, various methods
have been devised to achieve a larger palette; this is possi-
ble at the expense of spatial resolution. Because of this
tradeoff between effective resolution and the number of
colours which can be distinguished, the best method for a
given document depends on the contents of the document and
the user should therefore be able to select it.
The pcl3 driver supports the following methods for intensity
rendering:
printer use the printer's capabilities
directly
halftones use ghostscript's halftoning imple-
mentation
Floyd-Steinberg use Floyd-Steinberg error diffusion
The default method is halftones. The methods differ only in
their treatment of intensities which cannot be represented
directly by the printer. If your document contains for exam-
ple only black text, they all produce the same result, albeit
at different speeds.
With printer, pcl3 will cause everything to be painted at the
full hardware resolution but will have to map all colours to
the nearest levels the printer can represent directly. For a
CMY or CMYK printer with two intensity levels, this results
in just 8 useful colours per pixel. This value is therefore
usually only sensible for documents with a small number of
widely different saturated colours where accurate colour
reproduction is of minor importance but achieving the highest
possible resolution is essential. Another possible applica-
tion is the case of PostScript input which has already been
adapted to the printer's resolution and available intensity
levels.
With halftones, ghostscript will use what looks like standard
PostScript halftoning algorithms. For details, consult a
PostScript manual. However, you should know that
ghostscript's current halftoning implementation has some
problems:
o The algorithm cannot handle different non-zero values
for BlackLevels and CMYLevels. In this situation gs
will in general assume that the number of black levels
available is equal to that for CMY levels. Depending
on which of the numbers is smaller, there will then
either be unused black levels or some will be used more
than once.
o When you are using values larger than 2 for BlackLevels
or CMYLevels, ghostscript does not discover by itself
that it could now achieve the same number of shades
with smaller halftone cells.
o Most of the ways of increasing the halftone screen fre-
quency seem to fail. I have been successful only with
the somewhat pedestrian approach of using threshold
arrays, and even that worked only for some cases.
o For particular CMYK values and with ghostscript ver-
sion 6 or higher, the colour becomes drastically wrong.
One example is CMYK = (0.99998472, 0.002549, 0,
0.00367827); this should be almost a pure cyan but is
instead displayed as a sort of pink. If one subtracts
one unit in the last position for any of the non-zero
components, the result becomes acceptable. The problem
has not been observed with ghostscript 5.50.
o For ghostscript versions up to and including 5.50, if
you are using the colour model CMYK and more than 2
black levels you should not set merely a single
halftone screen (setscreen, a type-1 or a type-3
halftone dictionary) because ghostscript's dithering
routine can in this case return non-monotonic levels of
black for monotonic input intensities. However, if you
specify independent halftone information for the colour
components, gs uses a slower but more accurate algo-
rithm instead which does not lead to the wrong behav-
iour. It is not necessary for the halftone information
to be different for different components to achieve
this. Note that ghostscript installs separate halftone
screens for CMYK devices by default if the resolution
is at least 150 ppi.
Whenever you modify the halftone screens you should therefore
use a test file like levels-test.ps in the pcl3 distribution
to check whether you obtain the desired result. In particu-
lar, you should count the number of intensities you can dis-
tinguish for a single colorant: if it is obviously not one
plus the number of pixels in the halftone cell times one less
than the number of hardware intensity levels, something has
gone wrong. This is, for example, the case if you specified
4 black levels and a 2x2 halftone cell, and you then can dis-
tinguish more than 1 + 4x3 = 13 intensity levels. You should
also watch for non-monotonic jumps in intensity and incom-
pletely filled shapes.
The value Floyd-Steinberg selects Floyd-Steinberg error dif-
fusion as the method for rendering intensities. Use this in
particular for printing photographs and other documents with
a large number of colours or small irregular shapes. Regret-
tably, pcl3's speed is much slower with this method than in
the other cases, hence this value should only be used when it
is really needed (e.g., when you run into one of
ghostscript's halftoning problems) or when the delay is
acceptable.
If you are using ghostscript 5.50 and the page to be rendered
needs a lot of memory (this applies in particular to Floyd-
Steinberg in colour) a core dump may result under certain
circumstances. You can get around this by increasing the
MaxBitmap parameter or by switching to a newer ghostscript
version.
-dLeadingEdge=edge
This option can be used to specify which edge of the sheet
will enter the printer first. The permitted values identify
this edge by reference to the orientation of default user
space on the sheet when printing with default settings
(except for LeadingEdge) and a page size having width <=
height ("canonical page in portrait orientation"):
null No request for media orientation
0 Short edge; top of canonical page
1 Long edge; right side of canoni-
cal page
2 Short edge; bottom of canonical
page
3 Long edge; left side of canonical
page
As far as I know, given a particular PCL-3+ printer and a
particular media size, you cannot choose between short edge
first (0 or 2) and long edge first (1 or 3): this orientation
is prescribed by the manufacturer and should be documented in
your printer's manual. If in doubt, use short edge first
when inserting the medium.
The default value for edge is null. This leads either to 0
or to 3, depending on whether the subdevice normally expects
media of this size to be fed short edge first or long edge
first. See the subsection Media Sizes and Orientations in
the DESCRIPTION section above for details.
If you find that you can't set this parameter from PostScript
but you can set it from the command line, ghostscript's set-
pagedevice definition probably does not pass the parameter to
drivers. Read the gs-mods.txt file in the pcl3 distribution
on how to fix this.
-dManualFeed[=boolean]
It is possible to request a DeskJet printer to wait before
each page of a document until the Load/Eject button is
pressed on the printer. This is intended for situations
where some special medium is used or the medium has to be
inserted into an input slot holding only one sheet at a time.
The default setting for this option is false.
In PCL, manual feed is established by requesting a particular
media source (2), hence you should expect that setting this
parameter will interfere with the input tray selection via
InputAttributes (see the Media Sources and Destinations sub-
section in the CONFIGURATION section below).
-sMediaConfigurationFile=pathname
This option must specify an existing file containing a list
of supported media sizes, sheet orientations and correspond-
ing margin descriptions for the printer. This will take
precedence over the builtin subdevice-specific lists. The
format of the file is described in the CONFIGURATION section
below. This option is primarily intended to be used with the
subdevices unspecold and unspec.
The default is not to use a media configuration file but the
builtin lists. However, a media file path can also be speci-
fied at compile time overriding the default behaviour for
unspec only. Using the MediaConfigurationFile option in
addition will take precedence over the compiled-in media file
path.
-dMediaPosition=position
This option sets the standard PostScript page device parame-
ter MediaPosition to the specified value. The integer posi-
tion identifies an input tray for feeding media from and must
refer to an existing entry in the InputAttributes dictionary
(see the Media Sources and Destinations subsection in the
CONFIGURATION section below) in order to take effect. The
media selection process will use this entry in preference to
others provided it matches the media request. The default is
not to request a particular tray by position but to look for
a best match based on other properties. As ghostscript's
default configuration defines only one entry in InputAt-
tributes this option is ineffective unless you modify Inpu-
tAttributes.
With current ghostscript versions you can't use this parame-
ter to select a negative position. The driver will issue a
warning if you attempt it. If the entry is actually
selected, a rangecheck error from ghostscript will follow.
This restriction applies only to this device parameter, not
to permissible values for position numbers in InputAt-
tributes: if you want to use a negative position, you can do
so by making sure that it is the only matching entry or by
selecting it via Priority.
-sMedium=medium
This option selects the type of medium you wish to print on
as far as the printer needs to know about it. The possible
choices are:
0 plain paper
1 bond paper
2 HP Premium paper
3 glossy paper
4 transparency film
5 quick dry glossy
6 quick dry transparency
The default is plain paper. For medium, you can specify the
full strings (these are the standard values), the (in some
cases) one-word strings resulting from dropping "paper",
"film", and "HP", or an integer. Out-of-range numerical val-
ues generate a warning but are passed through to the printer
if you are using a group-3 subdevice. If you don't, the
effect is the same as specifying plain paper. The values 5
and 6 are unknown to most DeskJets; the only official excep-
tion I know of is the HP 2000C printer. Your printer's man-
ual should tell you which kinds of medium are supported.
-dOnlyCRD[=boolean]
This parameter influences the PCL code generated and should
only be specified for group-3 DeskJets. The default value is
false and leads to the new PCL command Configure Raster Data
being used only when it is necessary. Specifying true leads
to Configure Raster Data being used even in those cases where
older commands would be sufficient.
There are indications that printers with a PCL dialect of
"PCL Level 3 enhanced" need a value of true for this option
to enable some of their functionality.
-sPageCountFile=pathname
The pathname must specify either a non-existent file in a
directory with write permission or a writable file with a
single line containing a non-negative integer. In the first
case, pcl3 will create the file and insert the number of
pages printed, in the second case the number will be incre-
mented by that amount. Parallel invocations of gs are per-
mitted to use the same file. pcl3 will also make the initial
page count available in its page device dictionary.
This option is mainly intended for spooler backends calling
pcl3. It can be used to keep track of the total number of
pages printed and also for per-job accounting. I recommend
using this option for the first purpose and to make a note of
the values in the resulting files whenever you insert a new
ink cartridge. This will enable you to get an indication of
how much a printed page costs, and hence why it is a good
idea to use draft quality whenever possible and why you
should have bought a laser printer.
The driver can be compiled without this option present but on
a UNIX system I would not expect this to be done unless gs
offers the same functionality in a driver-independent manner
which it currently does not.
pcl3 is distributed with example files if-pcl3 and cups-pcl3
of Berkeley and CUPS spooler backends using this option.
-sPCLInit1=string and -sPCLInit2=string
These options can be used to insert additional PCL commands
into pcl3's output. Strings given to PCLInit1 will be sent
immediately after the initial Printer Reset command, the
value of PCLInit2 will be emitted shortly before the raster
data of the first page. The default is not to send any addi-
tional commands.
Don't use any of these options unless you understand PCL or
someone who does tells you which value to choose under which
circumstances.
Because not every possible string value can be passed from
the command line, these parameters are best set from a Post-
Script file.
-sPJLJob=[jobname]
This option can be used to surround the generated file with
Printer Job Language (PJL) commands declaring it to be a sin-
gle print job called jobname. If you omit jobname, you cre-
ate an unnamed job. The string jobname may not contain dou-
ble quotes or control characters except HT (the forbidden
byte codes are 0 to 8, 10 to 31, and 34).
Use this option if your printer understands PJL and you dis-
cover either that settings for one job influence the follow-
ing job or that the printer does not recognize the end of the
job (lights remain flashing or a control panel still displays
a processing message). If you send the generated PCL file
through a PJL filter, in particular one querying the
printer's state, omit this option and use the filter for this
purpose instead.
-sPJLLanguage=language
If a printer supports several command languages and PCL 3+ is
not the default, the printer must be told to switch to PCL 3+
at the beginning of the print job. Hewlett-Packard's print-
ers use a Printer Job Language (PJL) command for this pur-
pose. Specifying this option will switch the printer to lan-
guage for the duration of the job and back to the default at
the end.
This option is not usually necessary except that there are
indications that printers with a PCL dialect of "PCL Level 3
enhanced" need -sPJLLanguage=PCL3GUI to enable some of their
functionality.
You should never use the option unless you have a reliable
source for the values of language accepted by your printer,
for example the output from pcl3opts for a file generated by
an official driver for the printer in question. Values I
have seen so far are PCLSLEEK and PCL3GUI.
If you send the generated PCL file through a PJL filter, omit
this option and use the filter for this purpose instead.
-sPrintQuality=quality
There are three print quality settings:
-1 draft or econo
0 normal
1 presentation or best
The default is normal. You may specify the strings or an
integer. Out-of-range numerical values will generate a warn-
ing but are passed through to the printer if you have
selected a group-3 subdevice. If you haven't, the effect is
the same as specifying normal.
-dRasterGraphicsQuality=quality
This option is only available for old DeskJets (including
unspecold) and controls a trade-off between quality and print
speed. The possible values for quality are:
0 Use current control panel setting
1 Draft
2 High
Specifying this option overrides the default value derived
from Medium and PrintQuality.
-dSendBlackLast[=boolean]
When printing with four inks, a PCL-3+ printer expects the
colour information for a row of pixels in the order black,
cyan, magenta, and finally yellow (KCMY).
There exists at least one printer (Olivetti JP792) which
claims to accept PCL 3+ but expects the colour planes to
arrive in the order CMYK. If you have a printer with this
property, use this option. The default value is false.
-dSendNULs=number
Most HP drivers for newer DeskJet printers generate PCL files
starting with a sequence of 600 NUL characters, at least one
uses even 9600 NULs. I have seen no documentation of this
feature but I assume that in PCL the NUL character demands a
null operation, i.e., does nothing. Just in case such a NUL
sequence is useful under certain circumstances, this option
can be used to request it. (It has been suggested that this
is needed to get the printer to accept new PCL commands if
the previous print job was aborted in the middle of a com-
mand.) The value number specifies the number of NUL charac-
ters to send and must not be negative. The default is zero.
Note that initial NULs might confuse spooler backends which
try to determine the file type from the first few bytes of
the file contents.
There is no point in using this option if some other command
in your print pipeline will add Printer Job Language (PJL)
commands to the pcl3-generated file.
-dShingling=shingling
This option is only available for group-2 DeskJets (including
unspecold) and controls the number of passes the print head
makes over the medium. A higher number permits more neigh-
bouring pixels to be printed in separate passes, thereby
reducing the likelihood of the ink spreading into the next
pixel. The possible values for shingling are:
0 No shingling
1 2 passes (50% each pass)
2 4 passes (25% each pass)
Specifying this option overrides the default value derived
from Medium and PrintQuality.
-sSubdevice=subdevice
This option identifies the printer model for which the gener-
ated file is intended. The following names (mostly of
Hewlett-Packard DeskJet printers) are accepted for subdevice:
hpdj, hpdjplus, hpdjportable, hpdj310, hpdj320,
hpdj340, hpdj400, hpdj500, hpdj500c, hpdj510, hpdj520,
hpdj540, hpdj550c, hpdj560c, unspecold, hpdj600,
hpdj660c, hpdj670c, hpdj680c, hpdj690c, hpdj850c,
hpdj855c, hpdj870c, hpdj890c, hpdj1120c, unspec.
The correspondence with the real printer name is, I hope,
obvious. Note that hpdj does not select the hpdj driver
(this driver's predecessor) but configures the pcl3 driver
for the "classical" HP DeskJet.
With the exception of hpdj, unspec and unspecold, your gs
binary might support the subdevice names also as device
names, i.e., instead of specifying -sDEVICE=pcl3 -sSubde-
vice=subdevice you might be able to write -sDEVICE=subdevice.
Check ghostscript's list of available devices to find out
whether this is the case (gs -h).
The choice of subdevice primarily determines which resolu-
tions, colour models, intensity levels and media sizes the
driver will accept, where the output will appear on the page,
and to some extent what PCL code the driver will generate.
Several of the subdevices are treated identically.
The default subdevice is unspec. It is intended for new
PCL-3+ printers not explicitly supported by this driver. For
unspec, all subdevice-specific checks (e.g., supported reso-
lutions) are turned off. Supported media sizes and margin
settings are assumed to be identical with those for the
DeskJets 850C/855C/870C/890C, but you can and should use the
MediaConfigurationFile option or its compile-time equivalent
to override this. The PCL code generated assumes a new
DeskJet in the sense that it should be at least of the level
of a DeskJet 540 supporting the PCL commands Media Type and
Print Quality. If you specify unequal horizontal and verti-
cal resolutions or more than two levels of intensity per col-
orant and pixel, the printer must in addition understand the
Configure Raster Data command.
The subdevice unspecold is similar but behaves like a DeskJet
560C. It supports all colour models and all uniform resolu-
tions (the horizontal resolution is equal to the vertical
resolution).
If you choose to use unspec or unspecold it is your responsi-
bility to ensure that pcl3 is only called with parameter val-
ues the printer can handle. This applies in particular to
the resolution and the intensity levels.
If you set this parameter from a PostScript document you must
know that doing this re-initializes most of the pcl3 parame-
ters to their default values. If you set several page device
parameters in a single setpagedevice call the Subdevice
option will be treated first.
-dTumble[=boolean]
When duplex printing is requested (-dDuplex), this parameter
specifies whether the y axes of PostScript's default user
space on the two sides of the sheet (assumed to use the same
page size) point to the same edge or to opposite edges. The
default value false indicates the same edge and is usually
suitable for binding on the left while true indicates oppo-
site edges and should be used for binding at the top.
You should note that the interpretation of Tumble refers to
default user space: if a PostScript program has rotated the
user space coordinate system the association between the
page's apparent "up" direction and the binding edge will usu-
ally not be the one desired. You should watch for this in
particular when creating output in landscape orientation from
an application still generating PostScript Level 1 code. If
a ghostscript screen driver like x11 displays the pages with
the right side up you should have nothing to worry about,
even in the case of landscape orientation. (You must call gs
directly for this test, not via ghostview.) If the orienta-
tion between the two sides turns out to be wrong, you will
have to print again with the opposite value for Tumble. If
that does not help and you have a printer supporting only one
of the two possible duplex orientations, check the relative
order of restore and showpage in the document you printed
(see the DuplexCapability option above).
-dUseCard[=value]
This option should only be given when printing on A6 and with
a printer like the HP DeskJet 1120C which distinguishes
between A6 sheets and A6 postcards. The option can be used
to specifically request one of the alternatives. The default
value is null and means that sheets are preferred to post-
cards, but either is acceptable if supported. The other per-
mitted values are true and false.
This option applies to all page sizes set while ghostscript
executes and this includes the default size set at startup.
If you wish to use -dUseCard=true you will therefore usually
have to specify the PAPERSIZE option in the call, otherwise
an error will occur because there is no postcard variant for
the usual default sizes (ISO A4 and US Letter).
Option Combinations for Hardware Parameters
Not all combinations of colour model, resolution, number of intensity
levels, print quality and media type are accepted or make sense.
Unfortunately, Hewlett-Packard does not publicly release sufficient
information to find the best possible combinations. A good way to find
reasonable settings is to use pcl3opts on files generated by an offi-
cial driver for the printer. You should also check the file
reports.txt in the pcl3 distribution. In addition, I'll provide some
remarks here.
As a general rule, it is unprofitable to use a finer resolution than
300 ppi or more than 2 intensity levels for draft quality. A coarser
resolution in particular can reduce the time needed to generate and
transmit the file to the printer. Combined with draft quality this
leads to what HP calls an "EconoFast" mode.
As an exception, here are recommendations based on official HP documen-
tation for the DeskJet 1120C. The table lists the resolution and the
number of black or black and CMY levels if not 2.
Quality Gray CMYK
---------------------------------------------------------
draft 300 ppi 300 ppi
normal 300 ppi, 4 levels 300 ppi, (4,3) levels
presentation 600 ppi 300 ppi, (4,4) levels
These seem reasonable values for the supported series-800 DeskJets as
well.
Checking Page Device Parameters
As for all ghostscript drivers, pcl3's command line options correspond
to identically-named PostScript page device parameters and are accessi-
ble in the usual way. In particular, it is possible to read the value
of a parameter by letting gs execute a command like
currentpagedevice /parameter get ==
where parameter is the name of the parameter one would like to inspect,
for example BlackLevels. This is useful if you are in doubt whether
the driver has accepted your options. Of course, for printer-visible
parameters you can also use pcl3opts on the output file.
The ghostscript distribution contains a program uninfo.ps which dis-
plays the page device dictionary on standard output but does not
resolve nested dictionaries. The pcl3 distribution contains a similar
program dumppdd.ps which does not have this limitation.
CONFIGURATION
Media Configuration File
A media configuration file (media file for short) can be used to over-
ride the builtin subdevice-specific lists of supported media sizes and,
for each size, the sheet orientation in the input tray and the margins
enforced by the printer. This feature is mainly intended to be used in
conjunction with unspec and unspecold: if you have a model not directly
supported by this driver, look up the supported media sizes, the rules
for inserting media and the corresponding printable regions in your
printer's manual and enter them in a media file.
Caution:
Entering a media size in the file which is not really supported
by your printer is not useful: the PCL interpreter will simply
ignore the request to set this size, and printer and driver may
have diverging opinions about what the margins will be. If you
need to print on a medium of a size not supported by your
printer, choose a larger and printer-supported size in Post-
Script or via FIXEDMEDIA, shift the image if necessary, estab-
lish properly-positioned clipping regions within the real size,
and print. Or you could use a suitable page size recovery pol-
icy for PostScript's media selection process. However, if you
have a newer DeskJet supporting custom page sizes, all this is
not necessary.
Margin specifications are important for two reasons: the values for the
left and top margins determine how the output is positioned on the
page, and sufficiently large values for the right and bottom margins
prevent the print head being caught at the paper's edge and printing
beyond the sheet, respectively. Because DeskJet printers usually have
an inconveniently large bottom margin (usually 0.4-0.8 inches or 10-20
mm), one might be tempted to specify smaller values than listed in the
printer's manual. However, one user reported that this led to the
printer depositing a large wet blob of black ink at the bottom of the
page.
A line in the media file can be blank, a comment line (first non-blank
character is '#'), or one of the following:
unit unit
size left bottom right top
A unit line specifies in which units margin specifications in the fol-
lowing lines should be interpreted. unit can either be in (inch) or mm
(millimetre) with in being the default. A unit specification remains
in force until overridden by a following unit line.
The second kind of line states that the model supports a particular
media configuration and specifies the hardware margins in force for
that case. The size word consists of two parts: a keyword denoting the
extension and an optional suffix. The following keywords are accepted
(entries marked with an asterisk (*) are those used by the subdevice
unspec if no media file is employed; entries with a section/paragraph
sign (S) similarly identify the sizes used by unspecold):
Index3x5in US index card 3 x 5 in
EnvChou4 Japanese long envelope #4 (90 x 205
mm)
EnvMonarch US Monarch envelope (3.875 x 7.5
in)
*Postcard Japanese Hagaki card (100 x 148 mm)
*Index4x6in US index card 4 x 6 in
S*Env10 US no. 10 envelope (4.125 x 9.5 in)
A6 ISO/JIS A6 (105 x 148 mm)
*A6Card ISO/JIS A6 postcard (105 x 148 mm)
S*EnvDL ISO DL envelope (110 x 220 mm)
EnvUS_A2 US A2 envelope (4.375 x 5.75 in)
*EnvC6 ISO C6 envelope (114 x 162 mm)
EnvChou3 Japanese long envelope #3 (120 x
235 mm)
*Index5x8in US index card 5 x 8 in
Statement US Statement (5.5 x 8.5 in)
DoublePostcard double Postcard (148 x 200 mm)
*A5 ISO/JIS A5 (148 x 210 mm)
EnvC5 ISO C5 envelope (162 x 229 mm)
ISOB5 ISO B5 (176 x 250 mm)
*JISB5 JIS B5 (182 x 257 mm)
S*Executive US Executive (7.25 x 10.5 in)
S*A4 ISO/JIS A4 (210 x 297 mm)
S*Letter US Letter (8.5 x 11 in)
S*Legal US Legal (8.5 x 14 in)
EnvKaku2 Japanese Kaku envelope (240 x 332
mm)
JISB4 JIS B4 (257 x 364 mm). This is
distinct from ISO B4 (250 x 353
mm).
Tabloid US Tabloid (11 x 17 in; in land-
scape orientation also called
"Ledger")
A3 ISO/JIS A3 (297 x 420 mm)
HPSuperB what HP calls Super B (13 x 19 in)
*CustomPageSize custom page size
Note the difference between A6 (sheet) and A6Card (postcard). I do not
know why Hewlett-Packard associates this distinction with media size
instead of media type. However, with the exception of the 1120C all
DeskJet printers I know of use only A6Card anyway.
In looking at your printer's documentation, bear in mind that a driver
might support more sizes than the printer accepts; pcl3 needs to be
given the latter values. If you are in doubt what your printer under-
stands, pcl3opts can tell you which media size another driver requests.
Custom page sizes are not understood by older printers and may be used
in a media file only for the subdevices hpdj540, hpdj6nn[c], hpdj8nnc,
hpdj1120c, and unspec (group 3). In these cases you can print, within
certain limits, on arbitrarily-sized media. The driver knows these
limits and refuses to generate a file if you exceed them. For unspec,
there are no limits. pcl3 will tell the printer to expect a custom
page size only if there is no fitting discrete entry.
Although it is possible, on those printers which support it, to use a
media configuration file containing only a custom page size entry, I
advise against it because this size specification is only intended as a
last resort. If you have a custom page size entry in the media file,
you should therefore list all discrete sizes supported by your printer
or at least those which you expect to use.
The size keyword in the size field can be extended by the following
strings:
Big For pcl3, this suffix means banner printing. In these cases
the top and bottom margins are usually zero. HP DeskJets
supporting banner printing do so only for ISO A4 and US Let-
ter. Your media file should then contain entries for the
sizes A4, A4Big, Letter, and LetterBig.
.Transverse
By default, pcl3 assumes that the media listed are fed short
edge first. If you specify this qualifier, the driver will
assume that you are going to feed media of this size long
edge first. If, for example, your printer's manual states
that envelopes of size ISO DL should be fed long edge first,
the corresponding size field in your media file should con-
tain the string EnvDL.Transverse, not EnvDL.
This specification (or its absence) can be overridden with
the option LeadingEdge in the call.
The builtin lists for the unspec and unspecold devices do not contain
size entries with any of these suffixes.
Every media file must contain at least an entry which fits
ghostscript's default page size, usually ISO A4 or US Letter. Only
those sizes which are listed will be accepted by pcl3. This is inde-
pendent of a .Transverse suffix. If there are several entries in the
media file with the same size value, only the first is used.
The margins in a size entry should be valid for monochrome printing in
raster graphics mode. If a non-monochrome colour model is selected and
unless the bottom margin is exactly zero, it will be increased by a
subdevice-specific amount. This increment is zero for unspecold and
unspec.
The orientation of the margins refers to the feeding direction: you
should imagine holding the sheet such that the leading edge is at the
top and the side to be printed on is towards you. Be careful with
envelopes: older (pre-1997) HP documentation usually gives the margins
in landscape orientation even for those printers where the envelope has
to be fed short edge first. You can check this by looking for the
largest margin value: if it is on the left instead of at the bottom you
almost certainly have such a landscape-based specification; rotate the
values by +90 degrees (quarter-circle counterclockwise) in these cases.
The margins have to be specified as non-negative floating point numbers
in inches or millimetres as announced by the last preceding unit line.
The floating point format is that of the "C" locale.
pcl3 is distributed with an example of a media configuration file,
example.mcf.
PostScript Configuration Files
Sometimes it is desirable to execute additional PostScript commands for
a particular file or possibly all files sent to a particular printer or
print queue. With ghostscript this is easily possible because gs
accepts several file names in the invocation and processes them sequen-
tially. This is particularly appropriate for those PostScript opera-
tors which affect device-specific features and should therefore not
appear in a portable page description and for settings which would be
part of the interpreter's persistent state when using a real PostScript
printer.
The pcl3 distribution contains examples of filters if-pcl3 for the
Berkeley spooler lpr(1) and cups-pcl3 for the Common UNIX Printing Sys-
tem cupsd(8). These filters permit the use of a print-queue-specific
configuration file.
Media Sources and Destinations
PostScript has a builtin mechanism for selecting media sources and des-
tinations based on certain properties of the document. This usually
requires a system administrator to set the InputAttributes and Outpu-
tAttributes dictionaries in the device's page device dictionary accord-
ing to the current state of the printer and its intended use. For
example, if there are two input trays, one currently holding paper and
the other transparencies, the administrator could configure the Inpu-
tAttributes dictionary such that print jobs requesting transparencies
in a certain manner automatically fetch media from the second tray and
every job needing a size not currently available will terminate with an
error message. Unfortunately, in order to work as expected this
process usually also requires some additional action on the part of the
entity generating the PostScript code to be printed.
If your printer is capable of sensing certain properties of media in
the input tray (e.g., media size) or assumes a fixed association
between media properties and input trays you must expect this function-
ality to interfere with the process referenced here.
In the attributes dictionaries, each tray is identified by an integer,
its position number. When ghostscript successfully matches the docu-
ment's requirements with trays the resulting position numbers are
accessible to the driver. The pcl3 driver uses these numbers (except
0) directly as arguments for the PCL commands "Media Source" and "Media
Destination", respectively. For the Media Source values (input trays),
I know of the following meanings:
-1 banner printing
1 default tray; portable CSF
(DJ 340); tray 2 (HP
2500C)
2 manual feed
3 envelope feed
4 desktop CSF (DJ 340); tray
3 (HP 2500C)
5 tray 1 (HP 2500C)
7 auto select (HP 2500C)
You'll have to experiment with your printer to find out which values
are accepted and what their interpretation is. In general, you can
only expect 1 and 2 to work. Unrecognized values should be simply
ignored by the printer leading to the medium being fetched from the
default tray. To shorten the search, use pcl3opts if you can in order
to find out which values other drivers generate. Don't bother testing
the value 0: in PCL its effect is to eject a page and, as this is not
needed, pcl3 uses it to mean that no particular tray should be
selected.
I do not know of any PCL-3+ printer supporting more than one output
tray, hence the corresponding implementation is based on the specula-
tion that such a feature, if made available, would use the same command
as in PCL 5. Again, a value of zero is used by pcl3 to mean "don't
select a particular tray".
Ghostscript's default configuration defines InputAttributes and Outpu-
tAttributes dictionaries with one entry each, having position number 0
in both cases, and maps all requests to these positions. As explained
above, this configuration will lead to pcl3 not requesting any particu-
lar input or output tray. If you wish to modify this you should con-
sult a PostScript manual, for example the sections 6.2.1 and 6.2.4 in
the PostScript Language Reference. However, I'll present here three
examples without explanation. In all cases, the PostScript code shown
should be executed before the document to be printed.
The first example is intended for situations where you always wish to
select a specific input tray:
<<
/InputAttributes <<
0 null
input << /PageSize [6 6 524287 524287] >>
>>
>> setpagedevice
Replace input with the number of the tray you wish to use. The second
example does the same for the output tray:
<<
/OutputAttributes <<
0 null
output << >>
>>
>> setpagedevice
Replace output with the number of the tray you wish to use.
For the final example assume that you have one input tray, filled with
media of a certain default size, and you wish all print jobs requesting
another size to automatically switch to manual feed so you can insert
these special sheets at leisure. In that case, let gs execute the fol-
lowing PostScript code:
<<
/InputAttributes <<
0 << /PageSize [width height] >>
2 << /PageSize [6 6 524287 524287] >>
/Priority [0 2]
>>
>> setpagedevice
For width and height you must insert the actual dimensions of your
default size in units of 1 bp ("big point", 1/72 inch, roughly 0.35
mm); the tolerance is 5 bp. In contrast to a document's page size, the
orientation is irrelevant here.
If you drop the second entry and the Priority line in the last example
you obtain a configuration where ghostscript will refuse to print any
document not requesting the specified media size. If you retain the
two lines and you are using the unspecold or unspec devices it is
advisable to insert your printer's actual size bounds instead of those
given above. This will protect you against printing on some sizes not
supported by your printer.
Banner Printing
Some printers support printing on continuous forms, also called banners
or z-fold media. Your printer's manual should tell you whether this is
supported and in particular how to load these media.
In order to print on continuous media with pcl3, configure it as fol-
lows:
o Make sure that input position number -1 will be selected (see the
subsection Media Sources And Destinations above).
o In the call to gs, select a subdevice supporting the intended
"Big" size. By default, only the subdevices hpdj680c, hpdj690c
and hpdj1120c support banner printing (A4Big and LetterBig).
Don't forget to prepare the printer as well.
Correcting Offsets
A media configuration file is intended to adapt pcl3 to the difference
in margin settings between printer models and should usually contain
"official" information, preferably taken from the model's manual.
A different situation arises if a particular printer's output is not
properly positioned on the page even if the margin information is cor-
rect for this model. PostScript defines two arrays in the page device
dictionary for correcting such misadjustments, both containing two num-
bers describing a desired shift of the page image with respect to
device space coordinate axes but in different units. The values in the
`Margins' array are interpreted with respect to a canonical default
resolution, the newer `PageOffset' array is taken to be in units of
1/72 inch ("big points", bp). For pcl3 the device coordinate system
has an x axis pointing to the right and a y axis pointing downwards
when looking at the sheet with the leading edge at the top and the side
to be printed on towards you. The canonical default resolution is 300
ppi.
As an example, assume your printer shifts its output 1 mm to the right
and 0.5 mm upwards. Now create a file containing either the PostScript
code
<< /Margins [-11.8 5.9] >> setpagedevice
("shift 11.8 pixels to the left and 5.9 pixels down") or
<< /PageOffset [-2.8 1.4] >> setpagedevice
("shift 2.8 bp to the left and 1.4 bp down") and have it executed by
ghostscript before the file to be printed.
The margin test files distributed with pcl3 can be used to determine
the necessary correction. You should be aware that you have to expect
fluctuations between individual print jobs, in particular in the hori-
zontal direction.
Transfer Functions
DeskJets usually produce prints which are too dark (too much ink on the
page), most noticeably when using more than 2 intensity levels per col-
orant. In this case you should perform gamma correction by modifying
what PostScript calls transfer functions. In the simplest case, create
a file containing the PostScript command
{number exp} settransfer
where a good value for number is usually in the range 0.3-0.5, and
specify this file in ghostscript's command line before the file you
wish to print. Now the intensities of all colorants will be rescaled
by exponentiation with number. Because PostScript intensity values are
in the range zero to one with zero meaning dark and one meaning light
(additive interpretation), a value of number < 1 will lead to lighter
colours and number > 1 results in darker colours.
The best value for number depends on the print quality, the number of
intensity levels, the method chosen for intensity rendering, the kind
of medium you print on, and the properties of the document to be
printed.
Note that there is no common convention for the interpretation of
stand-alone gamma values. When dealing with other software you might
for example find that the boundary between light and dark is at a value
of 1000 and that lighter colours are obtained with larger values. In
order to understand what a "gamma value" means you therefore need the
complete specification of the transfer function and, if the value does
not refer to PostScript, also information on the interpretation of
intensity values.
You can also set independent transfer functions for the four colorants
by using the operator setcolortransfer which expects four routines as
arguments. Consult a PostScript manual if you want to learn more about
transfer functions.
If you are using -sIntensityRendering=halftones, less than 32 intensity
levels per colorant, a resolution below 800 ppi, and unless you explic-
itly set transfer functions, gs applies a default gamma correction
roughly corresponding to a value of 0.8 for number.
LIMITATIONS
Ghostscript Version
This manual page contains statements relying on undocumented properties
of ghostscript. These statements are to my best knowledge and belief
correct for current ghostscript versions but I do not check all these
statements for every new version.
If you are in doubt about a particular point, please check it yourself.
Reliability
Hewlett-Packard does not publicly provide sufficiently detailed or
accurate technical information to write a reliable driver for all of
its PCL-3+ printers. The amount and quality of available information
differs between printer models. As a consequence, pcl3 cannot provide
the same level of reliability for all of its devices.
In my opinion the best-documented printers are those of the DeskJet-500
series. In addition, I have currently access to a DeskJet 850C which I
have used for a number of experiments. Support for these printers
should be considered to be the most reliable.
The next level of reliability belongs to the remaining printers for
which subdevices exist. In these cases I had at least access to offi-
cial HP documentation on supported media sizes and associated hardware
margins and in addition for almost all cases some information on the
supported PCL commands, sometimes complemented by PCL files generated
by HP's official drivers and sent me by users.
The third level of reliability is associated with those printers for
which people have sent success reports but for which I have no official
information from HP.
With decreasing reliability it becomes increasingly probable that there
is printer functionality which is not accessible through pcl3 or even
that this driver generates PCL code not accepted by the printer.
Mixed Resolutions
Some printers are able to print with different resolutions for black
and CMY on the same region of a page. For example, the best quality on
a DeskJet 850C is achieved with 600 ppi for black and 300 ppi for CMY.
This is not supported by pcl3.
Photo Cartridges
From what I've heard, DeskJet printers with photo cartridges installed
do not use a CMYK palette but instead one with 6 components. I have no
official information on this interface and even if I had it wouldn't
help because ghostscript does not currently support DeviceN as a native
colour space.
Cartridge Alignment
DeskJet printers with more than one ink cartridge present should usu-
ally be configured for the proper relative alignment of these car-
tridges. Apparently, this information is stored in not-immediately-
volatile memory in the printer together with some settings (like the
default media size) which are not relevant for printing with pcl3. As
I do not have information on how this is done, you will need to use one
of HP's programs for this purpose.
On a Linux system, try installing and running HP's DOS DeskJet control
panel DJCP in the DOS emulator. DJCP should be present on one of the
installation media you received with your printer. One user managed to
get this to work for a DJ 670C with DOSEMU 0.98 under RedHat 5.2 by
setting
$_ports = "0x378 0x379"
in dosemu.conf. I was not successful on my Debian system.
The pcl3 distribution contains a file calign.ps which you can print if
you wish to check to which extent the cartridges are aligned.
KNOWN BUGS
There are no known bugs in pcl3 proper, but there do exist restrictions
or bugs in gs which can lead to faulty behaviour when printing with
pcl3. As far as I noticed them they are mentioned in the body of this
manual page at the relevant points.
You can find an up-to-date bug list for this driver via pcl3's home
page on the Web.
SEE ALSO
gs(1), pcl3opts(1)
A First Guide to PostScript (link to URL http://www.cs.indi-
ana.edu/docproject/programming/postscript/postscript.html)
Adobe Systems, PostScript Language Reference (link to URL http://part-
ners.adobe.com/asn/developer/PDFS/TN/PLRM.pdf) . Third edition, 1999.
AUTHOR
Copyright (C) 2000, 2001 by Martin Lottermoser, GreifswaldstraBe 28,
38124 Braunschweig, Germany. E-mail: Martin.Lottermoser@t-online.de.
pcl3 has a home page (link to URL http://home.t-online.de/home/Mar-
tin.Lottermoser/pcl3.html) on the Web.
This is free software, released under the terms of the GNU Lesser Gen-
eral Public License (LGPL) (link to URL http://www.gnu.org/copy-
left/lesser.html) , Version 2.1. USE IT AT YOUR OWN RISK.
Version of this reference page: $Revision: 1.21 $ ($Date: 2001/08/18
17:19:29 $).
pcl3 3.3 GS-PCL3(1)
NAME - SYNOPSIS - DESCRIPTION - OPTIONS - CONFIGURATION - LIMITATIONS -
KNOWN BUGS - SEE ALSO - AUTHOR -
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