GS-PCL3(1)GS-PCL3(1)NAME
pcl3 -- ghostscript device driver for printers understand
ing PCL 3+
SYNOPSIS
gs -sDEVICE=pcl3 [gs_option | -dBlackLevels=integer |
-dCMYLevels=integer | -sColorModel=model | -sColour
Model=model | -dCompressionMethod=method | -dConfig
ureEveryPage | -dCUPSAccounting | -dCUPSMessages |
-dDepletion=depletion | -dDryTime=seconds | -sDuplexCa
pability=capability | -sIntensityRendering=method |
-dLeadingEdge=edge | -dManualFeed | -sMediaConfigura
tionFile=pathname | -dMediaPosition=position |
-sMedium=medium | -dOnlyCRD | -sPageCountFile=pathname
| -sPCLInit1=string | -sPCLInit2=string | -sPJLJob=job_
name | -sPJLLanguage=language | -sPrintQuality=quality
| -dRasterGraphicsQuality=quality | -dSendBlackLast |
-dSendNULs=number | -dShingling=shingling | -sSubde
vice=subdevice | -dTumble | -dUseCard=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 appar
ently a not entirely compatible modification of PCL 3+.
This driver should basically 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 capabili
ties.
The driver does not support printers understanding only
Hewlett-Packard's PPA (Printing Performance Architecture)
commands. If a printer's documentation does not say any
thing 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-sup
plied 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 Subde
vice option for which model the generated PCL code is
intended. The model-dependent difference in the generated
code is not great. Apart from media specifications, reso
lutions and colour capabilities, one can consider three
groups of models which are treated with significant dif
ferences:
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 consists 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 subdevices 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 cur
rently 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/Mar_
tin.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) ver
sions of this driver were reported to work with the fol
lowing 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:
The printer has only a black ink cartridge.
The printer can print with either a black or a
cyan/magenta/yellow (CMY) cartridge.
The printer holds a CMY and a black cartridge simul
taneously, 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 bleeding".)
The printer holds a CMY and a black cartridge simul
taneously 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 mod
els. 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
converse does also occur. In addition, ghostscript is
generally fastest for Gray.
PCL 3+ also supports the colour model RGB although
Hewlett-Packard discourages its use. For this model the
printer internally converts the RGB data it receives into
CMY data for printing. Note that not everything which can
be demanded when using a CMY palette in PCL 3+ is also
permitted when using RGB. Because of its limited useful
ness, pcl3 accepts the colour model RGB only for the sub
devices 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 cur
rent 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 irre
spective 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:
the default size configured for gs (usually US
Letter or ISO A4 in portrait orientation),
the value given to the option PAPERSIZE in the invo
cation,
the size requested by the document, unless you spec
ify -dFIXEDMEDIA.
The last applicable item in this list overrides the oth
ers, hence the current page size can change at runtime.
The pcl3 driver splits the page size into sheet size and
page orientation 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 unsup
ported one is requested. (If you suspect that pcl3 is in
error concerning what is supported, check the list of sup
ported 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 necessary. (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 addi
tion every other size request as a custom page size with
out imposing any limits. If using any of these two subde
vices 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 mecha
nism is. The latter is usually specified 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 orien
tation") refers to the orientation of the sheet with
respect to the feeding direction, the latter ("page orien
tation") describes the orientation of the sheet with
respect to the page contents (default user space). These
orientations are logically independent: people inserting
paper into the printer need to know about the first, peo
ple composing documents only care about the latter.
Because pcl3 has no information about the actual dimension
or orientation 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 assumption 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 complete 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 sec
tion 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 proper
ties 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 val
ues are passed through to the printer, otherwise these
specifications are mapped to the older Depletion, Shin
gling, and Raster Graphics Quality commands based on rec
ommendations from HP. If you are not satisfied 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 "? compo_
nent:" 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 gener
ating 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 others as general tokens (-d), and
that gs effectively ignores every option it does not rec
ognize. 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 concen
trate first on the following ones, given here in the order
of their importance: -sDEVICE, -sSubdevice, -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.htm (link to URL Use.htm) and the
section Device parameters (link to URL Lan_
guage.htm#Device_parameters) in Language.htm).
-sDEVICE=pcl3
This specification selects the pcl3 driver, but
this is not the only way to select it with this
option. See the description 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 DuplexCapability 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 rein
serting 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 sub
device 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, 600300 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 interpretation: the value
given to pcl3 must be a resolution supported 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 600 300 ppi. How
ever, 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 600 300 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 levels except 1 up to 256. The subde
vices 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 doc
umentation):
You can't use this feature with draft
quality.
You can't use a colour model of CMY.
You must use a resolution of 300 ppi.
You must use 4 levels for black.
When using the subdevice unspec you should
expect the printer to similarly limit the possi
bilities. 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 levels 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
Models in the section DESCRIPTION above.
A value of CMY for this option also sets Black
Levels 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 happens
as for CMY. For all other situations you must
ensure yourself that colour model and intensity
levels are consistent 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 Pro
cessColorModel will not be correct for a colour
model of CMY or CMY+K. (Ghostscript returns the
native colour space in this parameter, not the
process colour model.)
-dCompressionMethod=method
PCL interpreters understand several compression
methods for raster graphics data in order to
speed up host-printer communication. The possi
ble choices are:
0 Unencoded, non-compressed
1 Runlength encoding
2 Tagged Image File Format
(TIFF) revision 4.0
"Packbits" encoding
3 Delta Row Compression
9 Compressed Replacement
Delta Row Encoding
The default method is 9 except for the subde
vices hpdj, hpdjplus, and hpdj500 where it is 3
(these printers do not support 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, depend
ing on the structure of the input. However,
although the absolute values change, the rela
tive 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, CUPSAccounting and CUPSMessages.
There exist, however, CUPS configurations where
page accounting messages should be generated by
a command further down the print pipeline than
pcl3 (e.g., by a CUPS backend capable of pro
cessing PJL Page Status 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 com
ponent in a CUPS (Common UNIX Printing System)
driver. It will modify the format of error mes
sages 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 depletion controls an algo
rithm 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 under
stood 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 Functions in the next
section).
-dDryTime=delay
With the exception of the DeskJets 500 and 500C,
series-500 DeskJet printers can be told to guar
antee 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 inte
gers in the range 0 to 1200, where null
instructs pcl3 not to send a corresponding com
mand, 0 establishes default values for the cur
rent print quality, and all other values explic
itly 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 identi
fied by the two possible values for the option
Tumble. Not all printers capable of duplex
printing, however, provide the hardware support
necessary 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 fol
lowing:
none no duplex capability
sameLeadingEdge second pass of sheet
occurs with the same
leading edge
oppositeLeadingEdge second pass of sheet
occurs with the oppo
site 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
oppositeLeadingEdge, but the printer permits
access to its duplex functionality only if you
specify in addition -sPJLLanguage=PCL3GUI -dOn
lyCRD. (Many thanks to Dawei W. Dong for an
extensive series of experiments.)
If a printer does not offer hardware support for
both orientations, 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 colorant. In the most
frequent case, merely two levels are possible.
As this is usually not sufficient, various meth
ods have been devised to achieve a larger
palette; this is possible at the expense of spa
tial 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 con
tents of the document and the user should there
fore 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 example
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 dif
ferent saturated colours where accurate colour
reproduction is of minor importance but achiev
ing the highest possible resolution is essen
tial. Another possible application is the case
of PostScript input which has already been
adapted to the printer's resolution and avail
able intensity levels.
With halftones, ghostscript will use what looks
like standard PostScript halftoning algorithms.
For details, consult a PostScript manual. How
ever, you should know that ghostscript's current
halftoning implementation has some problems:
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.
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.
Most of the ways of increasing the
halftone screen frequency seem to fail.
I have been successful only with the some
what pedestrian approach of using thresh
old arrays, and even that worked only for
some cases.
For particular CMYK values and with
ghostscript version 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.
For ghostscript versions up to and includ
ing 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 compo
nents, gs uses a slower but more accurate
algorithm instead which does not lead to
the wrong behaviour. It is not necessary
for the halftone information to be differ
ent for different components to achieve
this. Note that ghostscript installs sep
arate 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 par
ticular, you should count the number of intensi
ties you can distinguish 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, some
thing has gone wrong. This is, for example, the
case if you specified 4 black levels and a 22
halftone cell, and you then can distinguish more
than 1 + 43 = 13 intensity levels. You should
also watch for non-monotonic jumps in intensity
and incompletely filled shapes.
The value Floyd-Steinberg selects Floyd-Stein
berg error diffusion as the method for rendering
intensities. Use this in particular for print
ing photographs and other documents with a large
number of colours or small irregular shapes.
Regrettably, 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 switch
ing 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 com
mand line, ghostscript's setpagedevice defini
tion 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 spe
cial 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 inter
fere with the input tray selection via InputAt
tributes (see the Media Sources and Destinations
subsection in the CONFIGURATION section below).
-sMediaConfigurationFile=pathname
This option must specify an existing file con
taining a list of supported media sizes, sheet
orientations and corresponding margin descrip
tions for the printer. This will take prece
dence over the builtin subdevice-specific lists.
The format of the file is described in the CON_
FIGURATION section below. This option is pri
marily 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 specified at compile time
overriding the default behaviour for unspec
only. Using the MediaConfigurationFile option
in addition will take precedence over the com
piled-in media file path.
-dMediaPosition=position
This option sets the standard PostScript page
device parameter MediaPosition to the specified
value. The integer position 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 subsec
tion in the CONFIGURATION section below) in
order to take effect. The media selection pro
cess 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 con
figuration defines only one entry in InputAt
tributes this option is ineffective unless you
modify InputAttributes.
With current ghostscript versions you can't use
this parameter 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 posi
tion numbers in InputAttributes: 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
values generate a warning but are passed through
to the printer if you are using a group-3 subde
vice. 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
exception I know of is the HP 2000C printer.
Your printer's manual 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. Specify
ing 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 incremented by that amount. Parallel
invocations of gs are permitted 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 back
ends 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 func
tionality 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 back
ends 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 additional commands.
Don't use any of these options unless you under
stand 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 PostScript file.
-sPJLJob=[jobname]
This option can be used to surround the gener
ated file with Printer Job Language (PJL) com
mands declaring it to be a single print job
called jobname. If you omit jobname, you create
an unnamed job. The string jobname may not con
tain double 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 discover either that settings for one
job influence the following 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 par
ticular 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 printers use a
Printer Job Language (PJL) command for this pur
pose. Specifying this option will switch the
printer to language 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 -sPJLLan
guage=PCL3GUI to enable some of their function
ality.
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 offi
cial 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 warning 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 pix
els 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 gen
erate PCL files starting with a sequence of 600
NUL characters, at least one uses even 9600
NULs. I have seen no documentation of this fea
ture 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 command.) The value number
specifies the number of NUL characters 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 neighbour
ing 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 generated file is intended. The fol
lowing 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 predeces
sor) but configures the pcl3 driver for the
"classical" HP DeskJet.
With the exception of hpdj, unspec and
unspecold, your gs binary might support the sub
device names also as device names, i.e., instead
of specifying -sDEVICE=pcl3 -sSubdevice=subde_
vice you might be able to write -sDEVICE=subde_
vice. Check ghostscript's list of available
devices to find out whether this is the case (gs
-h).
The choice of subdevice primarily determines
which resolutions, colour models, intensity lev
els 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 gener
ate. 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-spe
cific checks (e.g., supported resolutions) 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 over
ride 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 vertical resolu
tions or more than two levels of intensity per
colorant 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 resolutions (the horizon
tal resolution is equal to the vertical resolu
tion).
If you choose to use unspec or unspecold it is
your responsibility to ensure that pcl3 is only
called with parameter values the printer can
handle. This applies in particular to the reso
lution and the intensity levels.
If you set this parameter from a PostScript doc
ument you must know that doing this re-initial
izes most of the pcl3 parameters 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 opposite edges and should
be used for binding at the top.
You should note that the interpretation of Tum
ble 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 usually not be the one desired. You
should watch for this in particular when creat
ing 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 orientation 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 orienta
tions, 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 specif
ically request one of the alternatives. The
default value is null and means that sheets are
preferred to postcards, but either is acceptable
if supported. The other permitted 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 rea
sonable settings is to use pcl3opts on files generated by
an official driver for the printer. You should also check
the file reports.txt in the pcl3 distribution. In addi
tion, I'll provide some remarks here.
As a general rule, it is unprofitable to use a finer reso
lution 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 offi
cial HP documentation 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 accessible in the usual way. In
particular, it is possible to read the value of a parame
ter 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 displays the page device dictionary on standard out
put 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 override the builtin subdevice-specific lists of
supported media sizes and, for each size, the sheet orien
tation 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 sup
ported 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 sup
ported by your printer, choose a larger and
printer-supported size in PostScript or via FIXED
MEDIA, shift the image if necessary, establish
properly-positioned clipping regions within the
real size, and print. Or you could use a suitable
page size recovery policy 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 out
put is positioned on the page, and sufficiently large val
ues 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 spec
ify 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 follow
ing:
unit unit
size left bottom right top
A unit line specifies in which units margin specifications
in the following 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 () similarly identify the
sizes used by unspecold):
Index3x5in US index card 3 5 in
EnvChou4 Japanese long envelope #4 (90 205
mm)
EnvMonarch US Monarch envelope (3.875 7.5
in)
*Postcard Japanese Hagaki card (100 148 mm)
*Index4x6in US index card 4 6 in
*Env10 US no. 10 envelope (4.125 9.5 in)
A6 ISO/JIS A6 (105 148 mm)
*A6Card ISO/JIS A6 postcard (105 148 mm)
*EnvDL ISO DL envelope (110 220 mm)
EnvUS_A2 US A2 envelope (4.375 5.75 in)
*EnvC6 ISO C6 envelope (114 162 mm)
EnvChou3 Japanese long envelope #3 (120
235 mm)
*Index5x8in US index card 5 8 in
Statement US Statement (5.5 8.5 in)
DoublePostcard double Postcard (148 200 mm)
*A5 ISO/JIS A5 (148 210 mm)
EnvC5 ISO C5 envelope (162 229 mm)
ISOB5 ISO B5 (176 250 mm)
*JISB5 JIS B5 (182 257 mm)
*Executive US Executive (7.25 10.5 in)
*A4 ISO/JIS A4 (210 297 mm)
*Letter US Letter (8.5 11 in)
*Legal US Legal (8.5 14 in)
EnvKaku2 Japanese Kaku envelope (240 332
mm)
JISB4 JIS B4 (257 364 mm). This is
distinct from ISO B4 (250 353
mm).
Tabloid US Tabloid (11 17 in; in land
scape orientation also called
"Ledger")
A3 ISO/JIS A3 (297 420 mm)
HPSuperB what HP calls Super B (13 19 in)
*CustomPageSize custom page size
Note the difference between A6 (sheet) and A6Card (post
card). I do not know why Hewlett-Packard associates this
distinction with media size instead of media type. How
ever, 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 understands, 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 usu
ally zero. HP DeskJets supporting banner print
ing do so only for ISO A4 and US Letter. 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 contain the
string EnvDL.Transverse, not EnvDL.
This specification (or its absence) can be over
ridden 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 Let
ter. Only those sizes which are listed will be accepted
by pcl3. This is independent 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 val
ues by +90 degrees (quarter-circle counterclockwise) in
these cases. The margins have to be specified as non-neg
ative 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 configura
tion 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 sequentially.
This is particularly appropriate for those PostScript
operators 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 per
sistent 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 Com
mon UNIX Printing System 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 destinations based on certain properties of
the document. This usually requires a system administra
tor to set the InputAttributes and OutputAttributes dic
tionaries in the device's page device dictionary according
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 adminis
trator could configure the InputAttributes 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 ter
minate 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 functionality to interfere with the
process referenced here.
In the attributes dictionaries, each tray is identified by
an integer, its position number. When ghostscript suc
cessfully matches the document'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 mean
ings:
-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 gener
ate. 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 speculation 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 InputAt
tributes and OutputAttributes 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 partic
ular input or output tray. If you wish to modify this you
should consult a PostScript manual, for example the sec
tions 6.2.1 and 6.2.4 in the PostScript Language Refer_
ence. 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 con
trast to a document's page size, the orientation is irrel
evant 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 spec
ified 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 particu
lar how to load these media.
In order to print on continuous media with pcl3, configure
it as follows:
Make sure that input position number -1 will be
selected (see the subsection Media Sources And Des_
tinations above).
In the call to gs, select a subdevice supporting the
intended "Big" size. By default, only the subde
vices hpdj680c, hpdj690c and hpdj1120c support ban
ner 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, prefer
ably 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 correct for this model. PostScript
defines two arrays in the page device dictionary for cor
recting such misadjustments, both containing two numbers
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 con
taining 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 horizontal 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 colorant. 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 intensi
ties 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 mean
ing 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 interpre
tation of stand-alone gamma values. When dealing with
other software you might for example find that the bound
ary 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 explicitly 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 undocu
mented properties of ghostscript. These statements are to
my best knowledge and belief correct for current
ghostscript versions but I do not check all these state
ments 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 consid
ered 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 official HP documentation on supported
media sizes and associated hardware margins and in addi
tion for almost all cases some information on the sup
ported 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 proba
ble 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 exam
ple, the best quality on a DeskJet 850C is achieved with
600 ppi for black and 300 ppi for CMY. This is not sup
ported by pcl3.
Photo Cartridges
From what I've heard, DeskJet printers with photo car
tridges 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 usually be configured for the proper relative
alignment of these cartridges. Apparently, this informa
tion 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 car
tridges 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 ALSOgs(1), pcl3opts(1)
A First Guide to PostScript (link to URL
http://www.cs.indiana.edu/docproject/program_
ming/postscript/postscript.html)
Adobe Systems, PostScript Language Reference (link to URL
http://partners.adobe.com/asn/developer/PDFS/TN/PLRM.pdf)
. Third edition, 1999.
AUTHOR
Copyright 2000, 2001 by Martin Lottermoser, Greifswald
strae 28, 38124 Braunschweig, Germany. E-mail: Mar
tin.Lottermoser@t-online.de.
pcl3 has a home page (link to URL http://home.t-
online.de/home/Martin.Lottermoser/pcl3.html) on the Web.
This is free software, released under the terms of the GNU
Lesser General Public License (LGPL) (link to URL
http://www.gnu.org/copyleft/lesser.html) , Version 2.1.
USE IT AT YOUR OWN RISK.
Version of this reference page: $Revision: 1.1 $ ($Date:
2002/07/12 16:11:41 $).
pcl3 3.3GS-PCL3(1)
