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<h2>Table of contents</h2>

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<li><a href="#Measurements">Notes on measurements</a></li>
<li><a href="#File_formats">Image file formats</a></li>
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<li><a href="#PNG">PNG file format</a></li>
<li><a href="#JFIF">JPEG file format (JFIF)</a></li>
<li><a href="#PNM">PNM file format</a></li>
<li><a href="#TIFF">TIFF file formats</a></li>
<li><a href="#fax">fax file formats</a></li>
<li><a href="#BMP">BMP file format</a></li>
<li><a href="#PCX">PCX file format</a></li>
<li><a href="#PSD">PSD file format (DeviceN color model)</a></li>
<li><a href="#High-level">High level formats</a></li>
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<li><a href="#PDF">PDF file output</a></li>
<li><a href="#PDFimage">Bitmap PDF output, PCLm output</a></li>
<li><a href="#PS">PostScript file output</a></li>
<li><a href="#EPS">EPS file output</a></li>
<li><a href="#PXL">PCL-XL file output</a></li>
<li><a href="#TXT">Text output</a></li>
<li><a href="#Dis    play_devices">Display devices</a></li>
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<li><a href="#x11_devices">X Window System</a></li>
<li><a href="#display_device">display device (MS Windows, OS/2, gtk+)</a></li>
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<li><a href="#IJS">IJS - Inkjet and other raster devices</a></li>
<li><a href="#Rinkj">Rinkj - Resplendent inkjet driver</a></li>
<li><a href="#HP_ijs">HP Deskjet official drivers</a></li>
<li><a href="#gimp-print">Gimp-Print driver collection</a></li>
<li><a href="#Win">MS Windows printers</a></li>
<li><a href="#SPARCprinter">Sun SPARCprinter</a></li>
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<li><a href="#SPARC_install">Installation</a></li>
<li><a href="#SPARC_problems">Problems</a></li>
<li><a href="#Apple">Apple dot matrix printer</a></li>
<li><a href="#Test">Special and Test devices</a></li>
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<li><a href="#Bit">Raw 'bit' output.</a></li>
<li><a href="#Bounding_box_output">Bounding Box output.</a></li>
<li><a href="#Ink_coverage_output">Ink coverage output.</a></li>
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<li><a href="#Permute">Permutation (DeviceN color model)</a></li>
<li><a href="#SPOT">spotcmyk (DeviceN color model)</a></li>
<li><a href="#XCF">XCF (DeviceN color model)</a></li>
<li><a href="#bitraw">Raw 'bit' devices</a></li>
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<p>For other information, see the <a href="Readme.htm">Ghostscript
overview</a>.  You may also be interested in <a href="Make.htm">how to
build Ghostscript</a> and <a href="Install.htm">install it</a>, as well as
the description of the <a href="Drivers.htm">driver interface</a>.</p>
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<p>Documentation for some older, superceded devices has been moved to
<a href="Deprecated.htm">another document</a>. In general such devices are deprecated
and will be removed in future versions of Ghostscript. In general all older printer
drivers can be replaced by the ijs interface and one of the available 3rd party raster
driver collections. We recommend moving to the ijs device for all such printing.</p>

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<h2><a name="Measurements"></a>Notes on measurements</h2>

Several different important kinds of measures appear throughout this
document: inches, centimeters and millimeters, points, and bits per pixel.</p>
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<dt>Centimeters and millimeters</dt>
<dd>ISO standard paper sizes such as A4 and A3 are commonly represented in
the SI units of centimeters and millimeters.  Centimeters are abbreviated
<dfn><abbr>cm</abbr></dfn>, millimeters <dfn><abbr>mm</abbr></dfn>.  ISO A4 paper is
quite close to 210&times;297 millimeters (approximately 8.3&times;11.7

<dd>1 inch equals 2.54 centimeters.  The inch measure is sometimes
represented by <dfn><abbr>in</abbr></dfn> or a quotation mark
(<abbr>&quot;</abbr>) to the right
of a measure, like 8.5in or 8.5&quot;.
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U.S. "letter" paper is exactly
8.5in&times;11in, approximately 21.6cm&times;27.9cm.  (See in the usage
documentation all the <a href="Use.htm#Known_paper_sizes">paper sizes
predefined in Ghostscript</a>.)</dd>

<dd>Points are a measure traditionally used in the printing trade and now
in PostScript, which specifies exactly 72 points per inch (approximately
28.35 per centimeter).  The <a href="Use.htm#Known_paper_sizes">paper sizes
known to Ghostscript</a> are defined in the initialization file
<code></code> in terms of points.</dd>
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<dt>Dots per inch</dt>
<dd>Dots per inch or <dfn><abbr>dpi</abbr></dfn> is the common measure of
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printing resolution in the US.</dd>

<dt>Bits per pixel</dt>
<dd>Commonly abbreviated <dfn><abbr>bpp</abbr></dfn> this is the number of
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digital bits used to represent the color of each pixel. This is also referred
to as 'bit depth' or 'pixel depth'.</dd>



<h2><a name="File_formats"></a>Image file formats</h2>

Ghostscript supports output to a variety of image file formats
and is widely used for rasterizing postscript and pdf files.
A collection of such formats ('output devices' in Ghostscript terminology)
are described in this section.

Here are some commonly useful driver options that apply to all raster drivers.
Options specific to particular file formats are described in their respective
sections below.</p>


<dd><p>This is a general option telling Ghostscript what to name the output.
It can either be a single filename '<code>tiger.png</code>' or a template
    '<code>figure-%03d.jpg</code>' where the <code>%03d</code> is replaced by the page number.</p></dd>
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<dd><p>This option sets the resolution of the output file in dots per inch.
The default value if you don't specify this options is usually 72 <abbr>dpi</abbr>.</p></dd>

<dd><p>These options control the use of subsample antialiasing. Their use is highly recommended
for producing high quality rasterizations of the input files. The size of the subsampling
box <em>n</em> should be 4 for optimum output, but smaller values can be used for faster
rendering. Antialiasing is enabled separately for text and graphics content.</p></dd>
<p>Because this feature relies upon rendering the input it is incompatible, and will generate
an error on attempted use, with any of the vector output devices.</p>
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It is also conventional to call Ghostscript with the '<code>-dSAFER -dBATCH -dNOPAUSE</code>' trio
of options when rasterizing to a file. These suppress interactive prompts and enable some
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security checks on the file to be run. Please see the <a href="Use.htm">Use documentation</a>
for a complete description.

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<h3><a name="PNG"></a>PNG file format</h3>

<p><acronym>PNG</acronym> (pronounced 'ping') stands for Portable Network Graphics,
and is the recommended format for high-quality images. It supports full quality
color and transparency, offers excellent lossless compression of the image data,
and is widely supported. Please see the
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<a href="" class="offsite">PNG website</a>
for a complete description of the format.</p>

<p>Ghostscript provides a variety of devices for <acronym>PNG</acronym> output
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varying by bit depth. For normal use we recommend <code>png16m</code> for 24-bit RGB color,
or <code>pnggray</code> for grayscale. The <code>png256</code>, <code>png16</code> and
<code>pngmono</code> devices respectively provide 8-bit color, 4-bit color and
black-and-white for special needs. The <code>pngmonod</code> device is also a
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black-and-white device, but the output is formed from an internal 8 bit grayscale
rendering which is then error diffused and converted down to 1bpp.</p>

<p>The <code>pngalpha</code> device is 32-bit RGBA color with transparency
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indicating pixel coverage.  The background is transparent unless
it has been explicitly filled.  PDF 1.4 transparent files do not
give a transparent background with this device.  Text and graphics
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anti-aliasing are enabled by default.</p>


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<p>The <code>pngmonod</code>, <code>png16m</code>, <code>pnggray</code> and
<code>pngalpha</code> devices all respond to the following:</p>
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<dd>This causes the internal rendering to be scaled down by the given (integer <= 8) factor before being output. For example, the following will produce
a 200dpi output png from a 600dpi internal rendering:</dd>
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 <kbd>gs -sDEVICE=png16m -r600 -dDownScaleFactor=3 -o tiger.png\
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<p>The <code>pngmonod</code> device responds to the following option:</p>
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<dt><code>-dMinFeatureSize=</code><em>state</em> (0 to 4; default = 1)</dt>
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<dd>This option allows a minimum feature size to be set; if any output pixel
appears on its own, or as part of a group of pixels smaller than
<code>MinFeatureSize</code> x <code>MinFeatureSize</code>, it will be expanded to
ensure that it does. This is useful for output devices that are high
    resolution, but that have trouble rendering isolated pixels.</dd>
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<dd>While this parameter will accept values from 0 to 4, not all are fully
implemented. 0 and 1 cause no change to the output (as expected). 2 works
as specified. Values of 3 and 4 are accepted for compatibility, but
behave as for 2.</dd>
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<p>The <code>pngalpha</code> device responds to the following option:</p>
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<dt><code>-dBackgroundColor=</code><b><em>16#RRGGBB</em></b> (RGB color, default white = 16#ffffff)</dt>
<dd>For the <code>pngalpha</code> device only,
set the suggested background color in the PNG bKGD chunk.
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When a program reading a PNG file does not support alpha
transparency, the PNG library converts the image using
either a background color if supplied by the program
or the bKGD chunk.
One common web browser has this problem, so when using
<code>&lt;body bgcolor="CCCC00"&gt;</code> on a web page
you would need to use <code>-dBackgroundColor=16#CCCC00</code>
when creating alpha transparent PNG images for use on the
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<p>Examples of how to use Ghostscript to convert postscript to PNG image files:</p>
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 <kbd>gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=png16m -dGraphicsAlphaBits=4 \
      -sOutputFile=tiger.png examples/tiger.png</kbd>

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 <kbd>gs -dSAFER -dBATCH -dNOPAUSE -r150 -sDEVICE=pnggray -dTextAlphaBits=4 \
      -sOutputFile=doc-%02d.png doc.pdf</kbd>

<h3><a name="JFIF"></a>JPEG file format (JFIF)</h3>

Ghostscript includes output drivers that can produce jpeg files
from postscript or pdf images. These are the <code>jpeg</code> and
    <code>jpeggray</code> devices.</p>
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<p>Technically these produce <a href="">Independent JPEG Group</a>
JFIF (JPEG File Interchange Format) files, the common sort found on the web.</p>

<p><strong>Please note</strong> that
JPEG is a compression method specifically intended for continuous-tone
images such as photographs, not for graphics, and it is therefore quite
unsuitable for the vast majority of page images produced with PostScript.
For anything other than pages containing simple images the lossy compression
of the jpeg format will result in poor quality output regardless of the input.
To learn more about the distinction, consult a reference about uses and abuses of JPEG,
such as the JPEG FAQ</p>
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<a href="" class="offsite"></a>


You can use the JPEG output drivers -- <code>jpeg</code> to produce
color JPEG files and <code>jpeggray</code> for grayscale JPEGs -- the
same as other file-format drivers: by specifying the device name and an
output file name, for example</p>
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<pre><kbd>gs -sDEVICE=jpeg -sOutputFile=foo.jpg</kbd></pre>


The JPEG devices support several special parameters to control the JPEG
"quality setting" (DCT quantization level).</p>

<dt><code>-dJPEGQ=</code><b><em>N</em></b> (integer from 0 to 100, default 75)</dt>
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<dd>Set the quality level <b><em>N</em></b> according to the widely used
IJG quality scale, which balances the extent of compression against the
fidelity of the image when reconstituted.  Lower values drop more
information from the image to achieve higher compression, and therefore
have lower quality when reconstituted.</dd>

<dt><code>-dQFactor=</code><b><em>M</em></b> (float from 0.0 to 1.0)</dt>
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<dd>Adobe's QFactor quality scale, which you may use in place of
<code>JPEGQ</code> above.  The QFactor scale is used by PostScript's
DCTEncode filter but is nearly unheard-of elsewhere.</dd>
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At this writing the default JPEG quality level of 75 is equivalent to
<code>-dQFactor=0.5</code>, but the JPEG default might change in the
future.  There is currently no support for any additional JPEG
compression options, such as the other DCTEncode filter parameters.

<h3><a name="PNM"></a>PNM</h3>

<p>The PNM (portable network map) family of formats are very simple
uncompressed image formats commonly used on unix-like systems. They
are particularly useful for testing or as input to an external conversion

<p>A wide variety of data formats and depths is supported. Devices include
   pbmraw pgm pgmraw pgnm pgnmraw pnm pnmraw ppm ppmraw pkm pkmraw pksm

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<h3><a name="TIFF"></a>TIFF file formats</h3>

<p><acronym>TIFF</acronym> is a loose collection of formats, now largely
superceded by <acronym>PNG</acronym> except in applications where backward
compatibility or special compression is required. The <acronym>TIFF</acronym>
file format is described in the
<a href="" class="offsite">TIFF 6.0 Specification</a>
published by Adobe Systems Incorporated.</p>
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<p>Note that, due to the structure of the TIFF format, writing TIFF output
requires that the target file be seekable. Writing to stdout, pipes or other
similar stream is not supported. Attempting to do so will generate an error.
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There are two unrelated sets of TIFF drivers.  There are five color TIFF
drivers that produce uncompressed output:</p>
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<dd>Produces 8-bit gray output.</dd>
<dd>Produces 12-bit RGB output (4 bits per component).</dd>
<dd>Produces 24-bit RGB output (8 bits per component).</dd>
<dd>Produces 48-bit RGB output (16 bits per component).</dd>
<dd>Produces 32-bit CMYK output (8 bits per component).</dd>
<dd>Produces 64-bit CMYK output (16 bits per component).</dd>
<a name="tiffsep"></a><dt><code>tiffsep</code></dt>
The <code>tiffsep</code> device creates multiple output files: a single 32 bit
composite CMYK file and multiple tiffgray files, one for each
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separation (unless <code>-dNoSeparationFiles</code> is specified). If separation
files are being produced and more than one page is being generated, the output file
specification <b>must</b> include a format specifier (e.g <code>-o outfile-%d.tif</code>)
so that each page can have a uniquely named set of separation files.</dd>
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<p>The default compression is <code>lzw</code> but this may be overridden by
the <code>-sCompression=</code> option.</p>
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The file specified via the OutputFile command line parameter will contain
CMYK data. This data is based upon the CMYK data within the file plus
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an equivalent CMYK color for each spot color. The equivalent
CMYK color for each spot color is determined using the alternate tint transform
function specified in the Separation and DeviceN color spaces. Since
this file is created based upon having color planes for each colorant, the
file will correctly represent the appearance of overprinting with spot colors.</p>
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File names for the separations for the CMYK colorants are created by appending
'.Cyan.tif', '.Magenta.tif' '.Yellow.tif' or '.Black.tif' to the
end of the file name specified via the OutputFile parameter.
File names for the spot color separation files are created by appending the
Spot color name in '(' and ').tif' to the filename.</p>
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If desired the file names for the spot color separation files can be created
by appending '.sn.tif'  (where n is the spot color number, see below) to the end
of the file name specified via the OutputFile parameter.   This change is a
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compile time edit.  To obtain this type of output the function
create_separation_file_name in gdevtsep.c should be called with a true value
for its use_sep_name parameter.</p>
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The <code>tiffsep</code> device will automatically recognize spot colors. In this
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case their order is determined by when they are found in the input file.
The names of spot colors may be specified via the SeparationColorNames
device parameters.</p>
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Internally each spot color is assigned a spot color number.  These
numbers start with 0 for the first spot color.  The spot color
numbers are assigned in the same order as the names are printed to
stderr (see below).  This order also matches the ordering in the
SeparationColorNames list, if this parameter is specified.  The
spot color numbers are not affected by the SeparationOrder parameter.</p>
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If only a subset of the colorants for a file is desired, then the separations
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to be output can be selected via the SeparationOrder
device parameter.  When colorants are selected via the
SeparationOrder parameter, the composite CMYK output contains
the equivalent CMYK data only for the selected colorants.</p>

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NOTE: the composite CMYK output, because it uses the tint transformed
colour equivalents for any spot colours (see Postscript Language
Reference "Separation Color Spaces" and "DeviceN Color Spaces"), may
not produce an accurate preview, if the job uses overprinting.</p>

The <code>tiffsep</code> device also prints the names of any spot colors
detected within a document to stderr.  (stderr is also used for the
output from the bbox device.)  For each spot color, the name of
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the color is printed preceded by '%%SeparationName:  '.  This
provides a simple mechanism for users and external applications to be informed about
the names of spot colors within a document.</p>
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Generally Ghostscript will support a maximum of 64 process and spot
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colors.   The <code>tiffsep</code> device the <code>psdcmyk</code> device
and the <code>psdcmyk16</code> devices maintain rendered data
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in a planar form with a maximum of 64 planes set by the definition of
GS_CLIENT_COLOR_MAX_COMPONENTS in the code.  That is there can be up to
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64 colorants accurately handled with overprint on a single page.  If more
than 64 colorants are encountered, those beyond 64 will be mapped to CMYK using the
alternate tint transform.</p>
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When rendering a PDF document,  Ghostscript can deteremine prior to rendering how
many colorants occur on a particular page.  With Postscript, this is not possible
in general.  To optimize for this, when rendering Postscript, it is possible to specify
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at run-time the number of spot colorants you wish to have the device capable
of handling using the -dMaxSpots=N command option, where N is the number of spot
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colorants that you wish to be able to handle and must be
less than 60 (60 + 4 CMYK process colorants gets us to a
maximum of 64 colorants on a page).   If you specify more than
is needed, the document will render more slowly.   The ideal case is to use
the same number as the maximum number of spot colorants that occur on a single page
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of the document.  If more spot colorants are encountered than is specified by
-dMaxSpots, then a warning will be printed indicating that some spot colorants will
be mapped to CMYK using the alternate tint transform.</p>

<p>The <code>tiffsep</code> device accepts a <code>-dBitsPerComponent=</code>
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option, which may be set to 8 (the default) or 1. In 1bpp mode, the
device renders each component internally in 8 bits, but then converts
down to 1bpp with error diffusion before output as described below in
the <code>tiffscaled</code> device. No composite file is produced in
1bpp mode, only individual separations.</p>

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<p>The device also accepts the <code>-dDownScaleFactor= -dTrapX= -dTrapy=</code> and
<code>-sPostRenderProfile=</code> parameters as described below in the tiffscaled device,
and <code>-dMinFeatureSize=</code> in 1bpp mode.</p>

<p>When <code>-dDownScaleFactor=</code> is used in 8 bit mode with the <code>tiffsep</code>
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(and <code>psdcmyk</code>/<code>psdrgb</code>/<code>psdcmyk16</code>/<code>psdrgb16</code>)
device(s) 2 additional &quot;special&quot; ratios
are available, 32 and 34. 32 provides a 3:2 downscale (so from 300 to
200 dpi, say). 34 produces a 3:4 upscale (so from 300 to 400 dpi, say).</p>

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<p>The <code>tiffscaled</code> and <code>tiffscaled4</code> devices
can optionally use Even Toned Screening, rather than simple Floyd Steinberg
error diffusion. This patented technique gives better quality at the
expense of some speed. While the code used has many quality tuning
options, none of these are currently exposed. Any device author
interested in trying these options should contact Artifex for more
information. Currently ETS can be enabled using -dDownScaleETS=1.</p>

<a name="tiffsep1"></a><dt><code>tiffsep1</code></dt>
The <code>tiffsep1</code> device creates multiple output files, one for each component
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or separation color. The device creates multiple tiffg4 files (the compression
can be set using -sCompression= described below). The 1 bit per component
output is halftoned using the current screening set by  'setcolorscreen'
or 'sethalftone' which allows for ordered dither or stochastic threshold
    array dither to be used. This is faster than error diffusion.</dd>
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The file specified via the OutputFile command line parameter will not be
created (it is opened, but deleted prior to finishing each page).</p>
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File names for the separations for the CMYK colorants are created by appending
'(Cyan).tif', '(Magenta).tif' '(Yellow).tif' or '(Black).tif' to the to the
end of the file name specified via the OutputFile parameter. File names
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for the spot color separation files are created by appending the Spot color
name in '(' and ').tif' to the filename.
If the file name specified via the OutputFile parameter ends with the suffix
'.tif', then the suffix is removed prior to adding the component name in
'(' and ').tif'.</p>

<a name="tiffscaled"></a><dt><code>tiffscaled</code></dt>
The <code>tiffscaled</code> device renders internally at the specified resolution to an
8 bit greyscale image. This is then scaled down by an integer scale factor
(set by <code>-dDownScaleFactor=</code> described below) and then error diffused to give
1bpp output. The compression can be set using -sCompression= as described
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<a name="tiffscaled4"></a><dt><code>tiffscaled4</code></dt>
The <code>tiffscaled4</code> device renders internally at the specified resolution to an
8 bit cmyk image. This is then scaled down by an integer scale factor
(set by <code>-dDownScaleFactor</code>= described below) and then error diffused to give
4bpp cmyk output. The compression can be set using -sCompression= as described

<a name="tiffscaled8"></a><dt><code>tiffscaled8</code></dt>
The <code>tiffscaled8</code> device renders internally at the specified resolution to an
8 bit greyscale image. This is then scaled down by an integer scale factor
(set by <code>-dDownScaleFactor</code>= described below). The compression can be set using
-sCompression= as described below.</dd>

<a name="tiffscaled24"></a><dt><code>tiffscaled24</code></dt>
The <code>tiffscaled24</code> device renders internally at the specified resolution to a
24 bit rgb image. This is then scaled down by an integer scale factor
(set by <code>-dDownScaleFactor</code>= described below). The compression can be set using
-sCompression= as described below.</dd>
610 611

<a name="tiffscaled32"></a><dt><code>tiffscaled32</code></dt>
The <code>tiffscaled32</code> device renders internally at the specified resolution to a
32 bit cmyk image. This is then scaled down by an integer scale factor
(set by <code>-dDownScaleFactor</code>= described below). The compression can be set using
-sCompression= as described below.</dd>

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The remaining TIFF drivers all produce black-and-white output with different
compression modes:</p>
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628 629 630 631 632 633 634 635 636 637 638 639
<dd>G3 fax encoding with no EOLs</dd>
<dd>G3 fax encoding with EOLs</dd>
<dd>2-D G3 fax encoding</dd>
<dd>G4 fax encoding</dd>
<dd>LZW-compatible (tag = 5) compression</dd>
<dd>PackBits (tag = 32773) compression</dd>
640 641 642

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<p>See the <code>AdjustWidth</code> option documentation below for important
information about these devices.</p>
645 646 647 648


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All TIFF drivers support creation of files that are comprised of more than a
single strip.  Multi-strip files reduce the memory requirement on the reader,
since readers need only store and process one strip at a time.  The
<code>MaxStripSize</code> parameter controls the strip size:</p>
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<dt><code>-dMaxStripSize=<em>N</em></code> (non-negative integer; default = 8192)</dt>
<dd>Set the maximum (uncompressed) size of a strip.</dd>
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660 661 662

The TIFF 6.0 specification, Section 7, page 27, recommends that the size of
each strip be about 8 Kbytes.</p>
664 665

If the value of the <code>MaxStripSize</code> parameter is smaller than a
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single image row, then no error will be generated, and the TIFF file will be
generated correctly using one row per strip.  Note that smaller strip sizes
increase the size of the file by increasing the size of the StripOffsets and
StripByteCounts tables, and by reducing the effectiveness of the compression
which must start over for each strip.</p>
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If the value of MaxStripSize is 0, then the entire image will be a single strip.</p>

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Since v. 8.51 the logical order of bits within a byte, FillOrder, tag = 266 is
controlled by a parameter:</p>
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<dt><code>-dFillOrder=<em>1 | 2 </em></code> (default = 1)</dt>
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<dd>If this option set to 2 then pixels are arranged within a byte such that pixels
with lower column values are stored in the lower-order bits of the byte; otherwise
pixels are arranged in reverse order.</dd>
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<p>Earlier versions of Ghostscript always generated TIFF files with FillOrder = 2.
According to the TIFF 6.0 specification, Section 8, page 32, support of
FillOrder = 2 is not required in a Baseline TIFF compliant reader</p>

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The writing of BigTIFF format output files is controlled with the
<code>-dUseBigTIFF</code> parameter.</p>
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Unfortunately, due the unpredictable size of compressed output, we cannot
automate the selection of BigTIFF, using it only when the output file
grows large enough to warrant it.</p>
700 701 702

703 704
<dt><code>-dUseBigTIFF(=<em>false/true</em>)</code> (boolean, default: false)</dt>
<dd>Force use (or not) of BigTIFF format in output from TIFF devices</dd>
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The writing of the DateTime TAG can be controlled using the
<code>-dTIFFDateTime</code> parameter.</p>
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<dt><code>-dTIFFDateTime(=<em>true/false</em>)</code> (boolean, default: true)</dt>
<dd>Write or otherwise the DateTime TAG to the TIFF output file. Thus to disable
writing the TAG, use: <code>-dTIFFDateTime=false</code></dd>
717 718 719

720 721
The compression scheme that is used for the image data can be set for all tiff
devices with:</p>
723 724 725

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    <dt><code>-sCompression=<em>none | crle | g3 | g4 | lzw | pack</em></code></dt>
    <dd>Change the compression scheme of the tiff device.
    <code>crle</code>, <code>g3</code>, and <code>g4</code> may only be
    used with 1 bit devices (including <code>tiffsep1</code>).</dd>
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For the <code>tiffsep</code> device, it changes the compression scheme
of the separation files and composite cmyk file (which is
<code>lzw</code> by default).  It defaults to <code>g4</code> for the
<code>tiffsep1</code> device.</p>
738 739

The black-and-white TIFF devices also provide the following parameters:</p>
741 742

<dt><code>-dAdjustWidth=<em>state</em></code> (0, 1, or value; default = 1)</dt>
<dd>If this option is 1 then if the requested page width is in the range
of either 1680..1736 or 2000..2056 columns, set the page width to A4
(1728 columns) or B4 (2048 columns) respectively. If this option is set
to a value &gt;1 then the width is unconditionally adjusted to this value.</dd>

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<dd>This behavior is the default for all the fax based devices (i.e. all the black
and white devices except <code>tifflzw</code>, <code>tiffpack</code> and
<code>tiffscaled</code>). Pass <code>-dAdjustWidth=0</code> to force this behaviour

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<dd>When using this option with <code>tiffscaled</code> it is the downsampled size
that triggers the adjustment.</dd>

<dt><code>-dMinFeatureSize=<em>state</em></code> (0 to 4; default = 1)</dt>
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<dd>This option allows a minimum feature size to be set; if any output pixel
appears on its own, or as part of a group of pixels smaller than
<code>MinFeatureSize</code> x <code>MinFeatureSize</code>, it will be expanded to
ensure that it does. This is useful for output devices that are high
resolution, but that have trouble rendering isolated pixels.</dd>
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<dd>While this parameter will accept values from 0 to 4, not all are fully
implemented. 0 and 1 cause no change to the output (as expected). 2 works
as specified. 3 and 4 currently expand pixels correctly horizontally, but
only expand vertically to the 2 pixel size.</dd>

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<dd>The mechanism by which <code>MinFeatureSize</code> is implemented for
<code>tiffscaled</code> is different, in that it is done as part of the error
diffusion. Values of 0 to 2 work as expected, but values 3 and 4 (while
accepted for compatibility) will behave as for 2.</dd>
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777 778 779
The <code>tiffscaled</code>, <code>tiffscaled4</code>, <code>tiffscaled8</code>,
<code>tiffscaled24</code> and <code>tiffscaled32</code> TIFF
drivers also provide the following two parameters:</p>
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<dt><code>-dDownScaleFactor=<em>factor</em></code> (small non-negative integer; default = 1)</dt>
783 784
<dd>If this option set then the page is downscaled by the given factor on both
axes before error diffusion takes place. For example rendering with
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<code>-r600</code> and then specifying <code>-dDownScaleFactor=3</code> will produce
a 200dpi image.</dd>
787 788

<dt><code>-sPostRenderProfile=<em>path</em></code> (path to an ICC profile)</dt>
<dd>If this option set then the page will be color transformed using that
profile <b>after</b> downscaling.</dd>
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This is useful when the file uses overprint to separately paint to some
subset of the C, M, Y, and K colorants, but the final CMYK is to be color
corrected for printing or display.</p>
797 798

The <code>tiffsep</code> TIFF device also provide this parameter:</p>
801 802 803 804 805

<dt><code>-dPrintSpotCMYK=<em>boolean</em></code> defaults to false. When set to true
the device will print (to stdout) the name of each ink used on the page, and the CMYK
values which are equivalent to 100% of that ink. The values are 16-bits ranging from 0
to 32760.</dt>
807 808 809 810 811 812

<a name="TIFF_trapping"></a>
<p>The <code>tiffsep</code> device (along with the <code>tiffscaled32</code> and
<code>psdcmyk</code> devices) can perform rudimentary automatic bitmap
'trapping' on the final rendered bitmap. This code is disabled by default; see
the <a href="#trapping_patent_note">note</a> below as to why.</p>
814 815 816 817 818 819

<p>Trapping is a process whereby the output is adjusted to minimise the
visual impact of offsets between each printed plane. Typically this involves
slightly extending abutting regions that are rendered in different inks. The
intent of this is to avoid the unsightly gaps that might be otherwise be
revealed in the final printout if the different color plates do not exactly
line up.</p>
821 822

<p>This trapping is controlled by 3 device parameters. Firstly the maximum
X and Y offsets are specified using <code>-dTrapX=N</code> and <code>-dTrapY=N</code>
(where <code>N</code> is a figure in pixels, before the downscaler is applied).</p>
825 826 827 828 829 830

<p>The final control is to inform the trapping process in what order inks
should be processed, from darkest to lightest. For a typical CMYK device
this order would be [ 3 1 0 2 ] (K darker than M darker than C darker than Y).
This is the default. In the case where CMYK + spots are used, the code
defaults to assuming that the spots are lighter than the standard colours
and are sent darkest first (thus [ 3 1 0 2 4 5 6 ... ]).</p>

<p>To override these defaults, the <code>TrapOrder</code> parameter can be used, for

    gs -sDEVICE=psdcmyk -dTrapX=2 -dTrapY=2 -o out.psd -c "&lt;&lt; /TrapOrder [ 4 5 3 1 0 2 ] &gt;&gt; setpagedevice" -f examples\tiger.eps

840 841
<h4><a name="trapping_patent_note"></a>Trapping patents</h4>

842 843 844
<p>Trapping is an technology area encumbered by many patents. We
believe that the last of these has now lapsed, and so have enabled
the code by default.</p>

846 847 848
<h3><a name="fax"></a>FAX</h3>

Ghostscript supports a variety of fax encodings, both encapsulated in
850 851 852 853 854
<acronym>TIFF</acronym> (see above) and as raw files. The later case is
described here.

The fax devices are <code>faxg3</code>, <code>faxg32d</code> and <code>faxg4</code>.
856 857

The fax devices support the <code>MinFeatureSize</code> parameter as defined in
860 861 862
the TIFF device section.

863 864 865 866
<h3><a name="BMP"></a>BMP</h3>

BMP is a simple uncompressed image format commonly used on MS Windows.
867 868
It is supported by the devices <code>bmpmono bmpgray bmpsep1
   bmpsep8 bmp16 bmp256 bmp16m bmp32b</code>.
869 870 871 872 873 874 875

<h3><a name="PCX"></a>PCX</h3>

PCX is an image format sometimes used on MS Windows. It has some support
for image compression and alternate color spaces, and so can be a useful
way to output CMYK.
It is supported by the <code>pcxmono pcxgray pcx16 pcx256 pcx24b pcxcmyk</code>
878 879 880 881 882 883 884
series of devices.

<h3><a name="PSD"></a>PSD</h3>

PSD is the image format used by Adobe Photoshop.
885 886 887
It is supported by the <code>psdcmyk</code>, <code>psdrgb</code>
<code>psdcmyk16</code> and <code>psdrgb16</code> devices.
Of special interest with the <code>psdcmyk</code> and <code>psdcmyk16</code> devices is that they support spot
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colors.  <a href="#tiffsep">See the comments under the <code>tiffsep</code> and <code>tiffsep1</code>
device about the maximum number of spot colors supported by Ghostscript</a></p>
891 892 893 894
The <code>psdcmyk16</code> and <code>psdrgb16</code> devices are essentially the same
as the <code>psdcmyk</code> and <code>psdrgb</code> devices except they provide 16 bit output.
The <code>psdcmykog</code> device produces PSD files with 6 components:
Cyan, Magenta, Yellow, blacK, Orange, and Green.  This device does not support the -dDownScaleFactor=
option (see below), instead it always scales down by a factor of two.</p>

900 901 902
These devices support the same -dDownScaleFactor= ratios as <code>tiffsep</code>.
The <code>psdcmyk</code> device supports the same trapping options as <code>tiffsep</code>
(but see <a href="#trapping_patent_note">this note</a>).</p>

904 905 906 907 908
NOTE: The PSD format is a single image per file format, so you must use the &quot%d&quot
format for the &quotOutputFile&quot (or &quot-o&quot) file name parameter (see
<a href="Use.htm#One_page_per_file">One_page_per_file</a> for details). An attempt
to output multiple pages to a single PSD file (i.e. without the &quot%d&quot format) will
909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932
result in an <code>ioerror</code> Postscript error.</p>

<h3><a name="PDFimage"></a>PDF image output</h3>

These devices render input to a bitmap (or in the case of PCLm multiple bitmaps) then wraps
the bitmap(s) up as the content of a PDF file. For PCLm there are some additional rules regarding
headers, extra content and the order in which the content is written in the PDF file.
The aim is to support the PCLm mobile printing standard, and
to permit production of PDF files from input where the graphics
model differs significantly from PDF (eg PCL and RasterOPs).
There are four devices named pdfimage8, pdfimage24, pdfimage32 and PCLm. These produce valid
PDF files with a colour depth of 8 (Gray), 24 (RGB) or 32 (CMYK), the PCLm device only supports 24-bit RGB.
These are all implemented as 'downscale' devices, which means they can implement page level
anti-aliasing using the <code>-dDownScaleFactor</code> switch.
<dd>This causes the internal rendering to be scaled down by the given (integer <= 8) factor before being output. For example, the following will produce
    a PDF containing a 200dpi output from a 600dpi internal rendering:</dd></dl>
934 935 936 937
 <kbd>gs -sDEVICE=pdfimage8 -r600 -dDownScaleFactor=3 -o tiger.pdf\
939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957

The type of compression used for the image data can also be selected using the <code>-sCompression</code> switch.
Valid compression types are <code>None</code>, <code>LZW</code>, <code>Flate</code>, <code>JPEG</code>
and <code>RLE</code>.Note that LZW is not supported on PCLm (not valid) and None is only supported
on PCLm for debugging purposes.
Finally, the PCLm device supports the <code>-dStripHeight</code> switch to set the vertical height
of the strips of image content, as required by the specification.

For JPEG compression the devices support both the JPEGQ and QFactor switches as documented for the <a href="#JFIF">JPEG</a> file format device.

958 959 960 961 962 963 964

In addition to raster image files, Ghostscript supports output in a number
of 'high-level' formats. These allow Ghostscript to preserve (as much as
possible) the drawing elements of the input file maintaining flexibility,
resolution independence, and editability.</p>

965 966
<h2><a name="High-level"></a>High-level devices</h2>

967 968
<h3><a name="PDF"></a>PDF writer</h3>

<p>The <code>pdfwrite</code> device outputs PDF.</p>

971 972
<h3><a name="PS"></a>PS2 writer</h3>

<p>The <code>ps2write</code> device outputs postscript language level 2.
It is recommnded that this device is used for PostScript output.
There is no longer any support for creating PostScript level 1 output.</p>

977 978
<h3><a name="EPS"></a>EPS writer</h3>

<p>The <code>eps2write</code> device outputs encapsulated postscript.</p>
980 981
<h3><a name="PXL"></a>PXL</h3>

982 983
<p>The <code>pxlmono</code> and <code>pxlcolor</code> devices output HP PCL-XL,
a graphic language understood by many recent laser printers.</p>


986 987 988
<h3><a name="TXT"></a>Text output</h3>

<p> The txtwrite device will output the text contained in the original
document as Unicode.</p>

991 992 993 994
<p>  Please refer to
<a href="VectorDevices.htm">VectorDevices.htm</a> for documentation on the
device options for these devices.
995 996 997 998 999 1000 1001 1002 1003 1004


<h2><a name="Display_devices"></a>Display Devices</h2>

Ghostscript is often used for screen display of postscript and pdf documents.
In many cases, a client or 'viewer' application calls the Ghostscript engine
to do the rasterization and handles the display of the resulting image itself,
but it is also possible to invoke Ghostscript directly and select an output
device which directly handles displaying the image on screen.</p>
1006 1007 1008

This section describes the various display-oriented devices that are available
in Ghostscript.</p>
1010 1011 1012 1013 1014 1015

<h3><a name="x11_devices"></a>X Window System</h3>

Perhaps the most common use of of a display device is with the X Window System
on unix-like systems. It is the default device on the command line client on
such systems, and is used more creatively by the gv client application.</p>
1017 1018

The available devices are:</p>
1020 1021

1022 1023
<dd>This is the default device, handling display on X11R6.</dd>

1025 1026 1027 1028
<dd>This is the <code>x11</code> device, but with antialiasing. It is equivalent to
invoking the <code>x11</code> device with the options <code>-dGraphicsAlphaBits=4
-dTextAlphaBits=4 -dMaxBitmap=50000000</code>.</dd>

<dd>This device rasterizes the image in the CMYK color space, then flattens
it to RGB for display. It's intended for testing only.</dd>

1034 1035
<dd>This is a strict black-and-white device for 1-bit monochrome displays.</dd>

1037 1038
<dd>This is a device for 2 bpp (4-level) monochrome displays.</dd>

1040 1041
<dd>This is a device for 4 bpp (16-level) monochrome displays.</dd>
1042 1043

1044 1045
<p>On Mac OS X as of 10.6, the X server (XQuartz) only supports color depth
15 and 24. Depth 15 isn't well-tested, and it may be desirable, for serious
use, to switch to depth 24 with:</p>
1047 1048 1049 1050 1051

defaults write org.x.X11 depth 24

1052 1053
<h3><a name="display_device"></a>display device (MS Windows, OS/2, gtk+)</h3>
The <code>display</code> device is used by the MS Windows,
1055 1056 1057 1058 1059 1060 1061 1062 1063
OS/2 and the gtk+ versions of ghostscript.


<p>The display device has several user settable options.</p>

<dt><code>-dDisplayFormat=</code><b><em>N</em></b> (integer bit-field)</dt>
<dd>Some common values are 16#30804 for Windows RGB, 16#804 for gtk+ RGB,
16#20101 for Windows monochrome, 16#102 for gtk+ monochrome,
16#20802 grayscale, 16#20808 for CMYK, 16#a0800 for separations.</dd>
1068 1069
The bit fields are
<li> native (1), gray (2), RGB (4), CMYK (8), or separation (80000)
1071 1072 1073 1074 1075 1076
color spaces.</li>
<li> unused first byte (40) or last byte (80).</li>
<li> 1 (100), 4 (400), or 8 (800) bits/component.</li>
<li> bigendian (00000 = RGB) or littleendian (10000 = BGR) order.</li>
<li> top first (20000) or bottom first (00000) raster.</li>
<li> 16 bits/pixel with 555 (00000) or 565 (40000) bitfields.</li>
1078 1079 1080
<p>For more details, see the <a href="API.htm#display">Ghostscript
Interpreter API.</a></p>
1081 1082 1083
<dd>Set the initial resolution resolution for the display device.
This is used by the Windows clients to set the display device
resolution to the Windows display logical resolution.
This can be overriden by the command line option
1086 1087 1088 1089


1090 1091
<p>When using the separation color space, the following options may be set
using setpagedevice, as described in the PostScript Language Reference:</p>
1092 1093 1094

1095 1096
<dd>An array giving the names of the spot colors</dd>

<dd>An array giving the names and order of the colorants
    to be output.</dd>
1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128


<h2><a name="IJS"></a>IJS - Inkjet and other raster devices</h2>

IJS is a relatively new initiative to improve the quality and ease of
use of inkjet printing with Ghostscript. Using IJS, you can add new
drivers, or upgrade existing ones, without recompiling Ghostscript.
All driver authors are encouraged to adapt their drivers for IJS, and
if there is an IJS driver available for your printer, it should be
your first choice.

<p>Please see the <a href="">IJS web
page</a> for more information about IJS, including a listing of
IJS-compatible drivers.

A typical command line for IJS is:

gs -dSAFER -sDEVICE=ijs -sIjsServer=hpijs
1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141
 -sDeviceManufacturer=HEWLETT-PACKARD -sDeviceModel='DESKJET 990'
 -dIjsUseOutputFD -sOutputFile=/dev/usb/lp1 -dNOPAUSE --

Individual IJS command line parameters are as follows:

1143 1144 1145 1146 1147 1148 1149
<dd>Sets the pathname for the IJS server (ie printer driver).
Ghostscript will spawn a new process for this driver, and communicate
with it using the IJS protocol. The pathname need not be absolute,
as the PATH environment variable is searched, but it's probably a good
idea for robustness and security. Note also that if -dSAFER is not
specified, it's possible for PostScript code to set this parameter,
so it can cause arbitrary code to be executed. See the section on <a
href="Use.htm#Security">Security</a> for more information.</dd>
1151 1152 1153

1154 1155
1156 1157 1158 1159
<dd>These parameters select the device according to IEEE-1284 standard
device ID strings. In general, consult the documentation for the
driver to find the appropriate settings. Note that, if the value
contains a space, you'll want to quote the value in your shell, as
in the example above.</dd>
1161 1162 1163

1165 1166 1167 1168 1169
<dd>This parameter allows you to set arbitrary IJS parameters on
the IJS driver. The format is a comma-separated list of
<code>key=value</code> pairs. If it is necessary to send a
value containing a comma or backslash, it can be escaped with
a backslash. Thus, <code>'-sIjsParams=Foo=bar,Baz=a\,b'</code> sets
the parameter Foo to "bar", and Baz to "a,b".</dd>
1171 1172 1173

1175 1176 1177 1178 1179
<dd>This flag indicates that Ghostscript should open the output file
and pass a file descriptor to the server. If not set, Ghostscript
simply passes the filename set in OutputFile to the server. In most
cases, this flag won't matter, but if you have a driver which works
only with OutputFD (such as hpijs 1.0.2), or if you're using the
-sOutputFile="|cmd" syntax, you'll need to set it.</dd>
1181 1182 1183

1185 1186
<dd>This parameter controls the number of bits per sample. The
default value of 8 should be appropriate for most work. For monochrome
images, use -dBitsPerSample=1.</dd>
1188 1189 1190 1191 1192 1193 1194

<p>Generic Ghostscript options that are particularly relevant for IJS
are summarized below:

1197 1198 1199
<dd>Sets the resolution, in dpi. If the resolution is not specified,
Ghostscript queries the IJS server to determine the preferred resolution.
When the resolution is specified, it overrides the value (if any)
preferred by the IJS server.</dd>
1201 1202 1203

1204 1205
1206 1207 1208 1209
<dd>These flags enable duplex (two-sided) printing. Tumble controls
the orientation. When Tumble is false, the pages
are oriented suitably at the left or right. When Tumble is true,
the pages are oriented suitably for binding at the top or
1211 1212 1213

<dd>Use this flag to select the process color model. Suitable values
include DeviceGray, DeviceRGB, and DeviceCMYK.</dd>
1217 1218 1219 1220 1221 1222

<h3>Building IJS</h3>

<p> IJS is included by default on Unix gcc builds, and also in
autoconf'ed builds. Others may need some makefile tweaking. First,
make sure the IJS device is selected:</p>
1224 1225

1227 1228 1229

<p> Next, make sure that the path and execution type are set in
the top level makefile. The values for Unix are as follows:</p>
1231 1232 1233 1234 1235 1236 1237 1238


<p> At present, "unix" and "win" are the only supported values for
IJSEXECTYPE. If neither sounds appropriate for your system, it's
possible that more porting work is needed.</p>
1240 1241

<p> Last, make sure that ijs.mak is included in the top level makefile.
It should be present right after the include of icclib.mak.</p>
1243 1244 1245 1246

<p> IJS is not inherently platform-specific. We're very much interested
in taking patches from people who have ported it to non-mainstream
platforms. And once it's built, you won't have to recompile Ghostscript
1247 1248
to support new drivers!</p>
1249 1250 1251 1252 1253 1254
<h2><a name="Rinkj"></a>Rinkj - Resplendent inkjet driver</h2>

<p>The Rinkj driver is an experimental new driver, capable of driving
some Epson printers at a very high level of quality. It is not
currently recommended for the faint of heart.</p>

<p>You will need to add the following line to your makefile:</p>
1256 1257

1259 1260 1261 1262 1263 1264 1265 1266 1267

<p>Most of the configuration parameters, including resolution, choice
of printer model, and linearization curves, are in a separate setup
file. In addition, we rely heavily on an ICC profile for mapping
document colors to actual device colors.</p>

<p>A typical command line invocation is:</p>

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gs -r1440x720 -sDEVICE=rinkj -sOutputFile=/dev/usb/lp0
  -sSetupFile=lib/rinkj-2200-setup -sProfileOut=2200-cmyk.icm
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Individual Rinkj command line parameters are as follows:

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<dd>Specifies the path for the setup file.</dd>

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<dd>Specifies the path for the output ICC profile. This profile should
be a <i>link</i> profile, mapping the ProcessColorModel (DeviceCMYK by
default) to the device color space.</dd>
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<p>For 6- and 7-color devices, the target color space for the output
profile is currently a 4-component space. The conversion from this
into the 6- or 7-color space (the "ink split") is done by lookup
tables in the setup file.</p>

<p>Setup files are in a simple "Key: value" text format. Relevant keys

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<dd>The manufacturer and model of the individual device, using the
same syntax as IEEE printer identification strings. Currently, the
only supported manufacturer string is "EPSON", and the only supported
model strings are "Stylus Photo 2200" and "Stylus Photo 7600".</dd>

<dd>The resolution in dpi. Usually, this should match the
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Ghostscript resolution set with the <code>-r</code> switch. Otherwise,
the page image will be scaled.</dd>

<dd>Selects among variant dither options. Currently, the choices are
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<code>1</code> for one-bit dither, and <code>2</code>, for a 2-bit variable
dot dither.</dd>

<dd>Controls the aspect ratio for highlight dot placement. Valid
values are <code>1</code>, <code>2</code>, and <code>4</code>. For best results,
choose a value near the x resolution divided by the y resolution. For
example, if resolution is 1440x720, aspect should be 2.</dd>

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<dd>Chooses a microdot size. On EPSON devices, this value is passed
directly through to the "ESC ( e" command. See EPSON documentation
for further details (see, I <em>told</em> you this wasn't for the
faint of heart).</dd>

<dd>Enables (1) or disables (0) unidirectional printing, which is
slower but possibly higher quality.</dd>

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<dd>Adds a linearization look-up table. The plane is one of
"CcMmYKk". The lookup table data follows. The line immediately
following AddLut is the number of data points. Then, for each data
point is a line consisting of two space-separated floats - the output
value and the input value. If more than one LUT is specified for a
single plane, they are applied in sequence.</dd>
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<p>A typical setup file is supplied in <code>lib/rinkj-2200-setup</code>.
It is configured for the 2200, but can be adapted to the 7600 just by
changing the "Model" line.</p>
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