gs-pcl3.ref

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<term>CMY</term>
<listitem><para>Print with cyan, magenta and yellow.
In this mode, "composite black" consisting of all three inks is used to
stand in for true black.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>CMY+K</term>
<listitem><para>
Print with all four inks, but never mix black with one of the others.
</para></listitem>
</varlistentry>
<varlistentry>
<term>CMYK</term>
<listitem><para>Print with all four inks.</para></listitem>
</varlistentry>
</variablelist></blockquote>

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:
<blockquote><informaltable><tgroup cols="2">
<thead>
  <row rowsep="1"><entry>DeskJet Model</entry><entry>Colour Models</entry></row>
  <!-- Rule missing here. -->
</thead>
<tbody>
  <row><entry>DeskJet, DeskJet Plus, DeskJet Portable, 500, 510, 520</entry>
    <entry>Gray</entry></row>
  <row><entry>310, 320, 340, 400, 500C, 540, 600</entry>
    <entry>Gray, CMY</entry></row>
  <row><entry>550C, 560C</entry><entry>Gray, CMY, CMY+K</entry></row>
  <row><entry>660C, 670C, 680C, 690C, 850C, 855C, 870C, 890C, 1120C</entry>
    <entry>all</entry></row>
</tbody>
</tgroup></informaltable></blockquote>

The subdevices <userinput>unspecold</userinput> and
<userinput>unspec</userinput> 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.
</para>

<para>
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.
</para>

<para>
PCL&nbsp;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&nbsp;3+ is also permitted when using RGB.
Because of its limited usefulness,
<command>pcl3</command> accepts the colour model RGB only for the subdevices
<userinput>unspecold</userinput> and <userinput>unspec</userinput>.
</para>

</refsect2>

<!--========================================================================-->

<refsect2 id="sizesAndOrientations"><title>Media Sizes and Orientations</title>

<para>
A PostScript document describes its visible content with respect to
a coordinate system called <firstterm>default user space</firstterm>.
Almost all PostScript devices are <firstterm>page devices</firstterm> which
paint only a restricted rectangular area in default user space.
Part of the state of a page device is therefore the current
<firstterm>page size</firstterm>,
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 &le; 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.
</para>

<para>
Ghostscript looks at several sources to determine the page size:
</para>
<itemizedlist>
<listitem><para>the default size configured for <command>gs</command>
(usually US Letter or ISO A4 in portrait orientation),
</para>
</listitem>
<listitem><para>the value given to the option <option>PAPERSIZE</option> in the
invocation,</para>
</listitem>
<listitem><para>the size requested by the document, unless you specify
<userinput>-dFIXEDMEDIA</userinput>.</para>
</listitem>
</itemizedlist>
<para>
The last applicable item in this list overrides the others,
hence the current page size can change at runtime.
</para>

<para>
The <command>pcl3</command> 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 <command>pcl3</command> 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 <firstterm>custom page size</firstterm> 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.)
<!-- The clj driver. -->
</para>

<para>
In setting up the PostScript default user space,
<command>pcl3</command>
does not treat envelope sizes differently from other sizes.
</para>
<!--
  The Adobe PostScript 3 Version 3010 and 3011 Product Supplement states
  (section 2.3, this is repeated from earlier versions of the Supplement) that
  for envelopes in portrait orientation the default user space origin should be
  in the corner opposite to the return address and not located on an edge where
  the flap is. For landscape orientation, the correct rotation of default user
  space is then -90 degrees ("seascape") instead of the usual +90 degrees
  used by setpagedevice. This implies that the generating program must treat
  envelopes different from other media of the same size! I find this
  unacceptable (and I could find stronger words than that).
  In addition, at least on a DJ 850C the way in which one should insert
  envelopes according to HP (flap on the right) leads to the expected result
  if one uses the +90 degrees rotation.
-->

<para>
The subdevice <userinput>unspecold</userinput> accepts all sizes supported by
the HP DeskJet 560C,
<userinput>unspec</userinput> 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
<link linkend="CONFIGURATION"><citetitle>CONFIGURATION</citetitle></link>
section below for details.
</para>

<para>
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.
</para>

<para>
Because <command>pcl3</command>
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 <literal>InputAttributes</literal>
definition (see the
<link linkend="sourcesAndDestinations"><citetitle>Media Sources and Destinations</citetitle></link>
subsection in the <citetitle>CONFIGURATION</citetitle> section below).
</para>

<para>
There is no command in PCL&nbsp;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
<command>pcl3</command> are correct or not:
the driver assumes that media are always fed short edge first except when
using the subdevices
<userinput>hpdj</userinput>,
<userinput>hpdjplus</userinput>,
<userinput>hpdj400</userinput>,
<userinput>hpdj500</userinput>
or
<userinput>hpdj500c</userinput>
for printing on envelope sizes
(US no. 10 and ISO DL).
In these cases you should insert the medium long edge first.
<!--
    Actually, this description is not entirely correct. The real assumption
    made by pcl3 is that if any PCL Page Size command is followed by a
    PCL Page Orientation command denoting "portrait", the first raster line
    sent is printed closest to and parallel with a short edge except in the
    cases mentioned in the text. The driver does not care how media are put
    into the input tray, but the medium's orientation with respect to the
    printer's command interface is important (and it's not documented by HP).

    The two descriptions are equivalent if the printer always prints the first
    raster line closest to and parallel with the leading edge. This assumption
    seems to me safe (mostly because PCL-3+ printers usually do not have
    sufficient memory to store a full graphics page) and I do not know of any
    PCL-3 printer violating it.
-->
If you find that <command>pcl3</command>'s default behaviour is incorrect,
you can override it with the option <option>LeadingEdge</option>
or a media configuration file
(see the
<link linkend="CONFIGURATION"><citetitle>CONFIGURATION</citetitle></link>
section below).
</para>

</refsect2>

<!--========================================================================-->

<refsect2><title>Print Quality and Media Properties</title>

<para>
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.
</para>

<para>
You can use the <option>PrintQuality</option> and
<option>Medium</option> 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.
<!-- See TRG, page 6-34. -->
If you are not satisfied with the result in the latter case,
use the options <option>Depletion</option>,
<option>Shingling</option> and
<option>RasterGraphicsQuality</option>
to explicitly set these values.
</para>

</refsect2>

<!--========================================================================-->

<refsect2><title>Diagnostic Messages</title>

<para>
Error messages issued by this driver start with
"<computeroutput>? <replaceable>component</replaceable>:</computeroutput>"
and warnings with
"<computeroutput>?-W <replaceable>component</replaceable>:</computeroutput>".
The <replaceable>component</replaceable> can be
<computeroutput>eprn</computeroutput>,
<computeroutput>pcl3</computeroutput>, or
<computeroutput>pclgen</computeroutput>,
corresponding to the driver's three internal layers:
the <command>eprn</command> device extends ghostscript without knowing PCL,
<command>pclgen</command> is a module generating PCL without being aware of
ghostscript,
and <command>pcl3</command> is the driver proper connecting the other two
layers.
</para>

<para>
All these messages are written on the standard error stream.
</para>

</refsect2>
</refsect1>

<!-- ********************************************************************** -->

<refsect1 id="OPTIONS"><title>OPTIONS</title>

<para>
When specifying options for <command>gs</command> you should keep in mind
that
case is significant,
that some options must be passed as strings (<userinput>-s</userinput>)
and others as general tokens (<userinput>-d</userinput>),
and that <command>gs</command>
effectively ignores every option it does not recognize.
Hence some care in spelling parameter names is necessary.
</para>

<para>
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:
<userinput>-sDEVICE</userinput>,
<userinput>-sSubdevice</userinput>,
<userinput>-sColourModel</userinput>,
<userinput>-r</userinput>,
<userinput>-sPrintQuality</userinput>,