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pcl3 --- ghostscript device driver for printers understanding PCL 3+
gs -sDEVICE=pcl3 [gs_option | -dBlackLevels=integer | -dCMYLevels=integer | -sColorModel=model | -sColourModel=model | -dCompressionMethod=method | -dConfigureEveryPage | -dCUPSAccounting | -dCUPSMessages | -dDepletion=depletion | -dDryTime=seconds | -sDuplexCapability=capability | -sIntensityRendering=method | -dLeadingEdge=edge | -dManualFeed | -sMediaConfigurationFile=pathname | -dMediaPosition=position | -sMedium=medium | -dOnlyCRD | -sPageCountFile=pathname | -sPCLInit1=string | -sPCLInit2=string | -sPJLJob=jobname | -sPJLLanguage=language | -sPrintQuality=quality | -dRasterGraphicsQuality=quality | -dSendBlackLast | -dSendNULs=number | -dShingling=shingling | -sSubdevice=subdevice | -dTumble | -dUseCard=value ] ... [file ...]
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 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 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 generated PCL code is intended. The model-dependent difference in the generated 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:
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 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.
Ignoring photo cartridges which are not supported by pcl3, DeskJet printers can be classified in four categories:
This leads to four (process) colour models for the driver:
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 Portable, 500, 510, 520 | Gray |
| 310, 320, 340, 400, 500C, 540, 600 | Gray, CMY |
| 550C, 560C | Gray, CMY, CMY+K |
| 660C, 670C, 680C, 690C, 850C, 855C, 870C, 890C, 1120C | all |
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 usefulness, pcl3 accepts the colour model RGB only for the subdevices unspecold and unspec.
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:
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 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 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 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 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 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 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 orientations 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 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 Destinations 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 section below).
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 specifications are mapped to the older Depletion, Shingling, and Raster Graphics Quality commands based on recommendations 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.
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 generating 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.
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 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 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.
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 Language.htm#Device_parameters) in Language.htm).
| 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 subdevices 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.
| 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 Functions in the next section).
| none | no duplex capability |
| sameLeadingEdge |
second pass of sheet occurs with the same leading 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.
| printer |
use the printer's capabilities directly
|
| halftones |
use ghostscript's halftoning implementation
|
| 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.
| null | No request for media orientation |
| 0 | Short edge; top of canonical page |
| 1 |
Long edge; right side of canonical page
|
| 2 |
Short edge; bottom of canonical page
|
| 3 |
Long edge; left side of canonical page
|
| 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 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 exception I know of is the HP 2000C printer. Your printer's manual should tell you which kinds of medium are supported.
| -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.
| 0 | Use current control panel setting |
| 1 | Draft |
| 2 | High |
Specifying this option overrides the default value derived from Medium and PrintQuality.
| 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.
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 official 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 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.
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 parameter by letting gs execute a command like
currentpagedevice /parameter get ==
The ghostscript distribution contains a program uninfo.ps which displays 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.
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 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.
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 PostScript or via FIXEDMEDIA, 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 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 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 в 5 in |
| EnvChou4 |
Japanese long envelope #4 (90 в 205 mm)
|
| EnvMonarch |
US Monarch envelope (3.875 в 7.5 in)
|
| *Postcard | Japanese Hagaki card (100 в 148 mm) |
| *Index4x6in | US index card 4 в 6 in |
| ╖*Env10 | US no. 10 envelope (4.125 в 9.5 in) |
| A6 | ISO/JIS A6 (105 в 148 mm) |
| *A6Card | ISO/JIS A6 postcard (105 в 148 mm) |
| ╖*EnvDL | ISO DL envelope (110 в 220 mm) |
| EnvUS_A2 | US A2 envelope (4.375 в 5.75 in) |
| *EnvC6 | ISO C6 envelope (114 в 162 mm) |
| EnvChou3 |
Japanese long envelope #3 (120 в 235 mm)
|
| *Index5x8in | US index card 5 в 8 in |
| Statement | US Statement (5.5 в 8.5 in) |
| DoublePostcard | double Postcard (148 в 200 mm) |
| *A5 | ISO/JIS A5 (148 в 210 mm) |
| EnvC5 | ISO C5 envelope (162 в 229 mm) |
| ISOB5 | ISO B5 (176 в 250 mm) |
| *JISB5 | JIS B5 (182 в 257 mm) |
| ╖*Executive | US Executive (7.25 в 10.5 in) |
| ╖*A4 | ISO/JIS A4 (210 в 297 mm) |
| ╖*Letter | US Letter (8.5 в 11 in) |
| ╖*Legal | US Legal (8.5 в 14 in) |
| EnvKaku2 |
Japanese Kaku envelope (240 в 332 mm)
|
| JISB4 |
JIS B4 (257 в 364 mm).
This is distinct from ISO B4 (250 в 353 mm).
|
| Tabloid |
US Tabloid (11 в 17 in; in landscape orientation also called "Ledger")
|
| A3 | ISO/JIS A3 (297 в 420 mm) |
| HPSuperB | what HP calls Super B (13 в 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 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:
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 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 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.
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 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 System cupsd(8). These filters permit the use of a print-queue-specific configuration file.
PostScript has a builtin mechanism for selecting media sources and destinations based on certain properties of the document. This usually requires a system administrator to set the InputAttributes and OutputAttributes dictionaries 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 administrator 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 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 functionality 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 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 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 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 InputAttributes 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 particular input or output tray. If you wish to modify this you should consult 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
<<
/OutputAttributes <<
0 null
output << >>
>>
>> setpagedevice
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 following 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.
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 follows:
Don't forget to prepare the printer as well.
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 correct for this model. PostScript defines two arrays in the page device dictionary for correcting 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 containing either the PostScript code
<< /Margins [-11.8 5.9] >> setpagedevice
<< /PageOffset [-2.8 1.4] >> setpagedevice
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.
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 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 explicitly set transfer functions, gs applies a default gamma correction roughly corresponding to a value of 0.8 for number.
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.
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 official 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.
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.
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.
DeskJet printers with more than one ink cartridge present should usually be configured for the proper relative alignment of these cartridges. 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"
The pcl3 distribution contains a file calign.ps which you can print if you wish to check to which extent the cartridges are aligned.
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.
A First Guide to PostScript (link to URL http://www.cs.indiana.edu/docproject/programming/postscript/postscript.html)
Adobe Systems, PostScript Language Reference (link to URL http://partners.adobe.com/asn/developer/PDFS/TN/PLRM.pdf) . Third edition, 1999.
Copyright © 2000, 2001 by Martin Lottermoser, Greifswaldstraъe 28, 38124 Braunschweig, Germany. E-mail: [email protected].
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: 1.21 $ ($Date: 2001/08/18 17:19:29 $).
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