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<!doctype html>
<html lang="en">
<head>
    <meta http-equiv="content-type" content="text/html; charset=utf-8">
    <meta name="viewport" content="user-scalable=yes, initial-scale=1, width=device-width">
    <link href="https://fonts.googleapis.com/css?family=Source+Sans+Pro:200,200i,300,300i,400,400i,600,600i,700,700i,900,900i" rel="stylesheet">
    <link rel="shortcut icon" href="images/favicon.svg">
    <title>Details of Ghostscript Output Devices</title>
    <link href="default.css" rel="stylesheet" type="text/css">
</head>

<body>
    <header><div class="title"><a href="index.html"><h1 aria-label="title">Ghostscript documentation</h1><h2 aria-label="version"></h2></a></div><a href="Search.htm" aria-label="Search" id="searchSite"><div class="search"></div></a></header>
    <main>
        <article>
            <div class="outer">

                <div class="inner">
<!--START EDITING HERE-->

<h1>Details of Ghostscript Output Devices</h1>

<h2><a name="toc"></a>Table of contents</h2>
<ul class="toc">
    <li><a href="#Measurements">Notes on measurements</a></li>
    <li><a href="#File_formats">Image file formats</a></li>
        <li>
            <ul>
                <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="#PDFimage">Bitmap PDF output, PCLm output</a></li>
            </ul>
        </li>
    <li><a href="#OCR-Devices">OCR Devices</a></li>
    <li>
        <ul>
            <li><a href="#OCR">OCR text output</a></li>
            <li><a href="#PDFocr">Bitmap PDF output (with OCR text)</a></li>
            <li><a href="#PDFwriteocr">Vector PDF output (with OCR Unicode CMaps)</a></li>
        </ul>
    </li>
    <li><a href="#High-level">High level formats</a></li>
    <li>
        <ul>
            <li><a href="#PDF">PDF file output</a></li>
            <li><a href="#OCR">OCR devices</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>
        </ul>
    </li>
    <li><a href="#Display_devices">Display devices</a></li>
    <li>
        <ul>
            <li><a href="#x11_devices">X Window System</a></li>
            <li><a href="#display_device">display device (MS Windows, OS/2, gtk+)</a></li>
        </ul>
    </li>
    <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>
    <li>
        <ul>
            <li><a href="#SPARC_install">Installation</a></li>
            <li><a href="#SPARC_problems">Problems</a></li>
        </ul>
    </li>
    <li><a href="#Apple">Apple dot matrix printer</a></li>
    <li><a href="#Test">Special and Test devices</a></li>
    <li>
        <ul>
            <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>
            <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>
        </ul>
    </li>
</ul>



<!-- [1.2 end table of contents] =========================================== -->

<!-- [1.3 begin hint] ====================================================== -->

<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>

<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>

<!-- [1.3 end hint] ======================================================== -->

<hr>

<!-- [1.0 end visible header] ============================================== -->

<!-- [2.0 begin contents] ================================================== -->

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

<p>
Several different important kinds of measures appear throughout this
document: inches, centimeters and millimeters, points, and bits per pixel.</p>

<dl>

<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
inches).</dd>

<dt>Inches</dt>
<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;.
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>

<dt>Points</dt>
<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>gs_statd.ps</code> in terms of points.</dd>

<dt>Dots per inch</dt>
<dd>Dots per inch or <dfn><abbr>dpi</abbr></dfn> is the common measure of
printing resolution in the US.</dd>

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

</dl>

<hr>

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

<p>
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.
</p>

<p>
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>

<blockquote><dl>

<dt>-sOutputFile=<em>filename</em></dt>
<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>


<dt>-r<em>res</em></dt>
<dt>-r<em>xres</em>x<em>yres</em></dt>
<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>

<dt>-dTextAlphaBits=<em>n</em></dt>
<dt>-dGraphicsAlphaBits=<em>n</em></dt>
<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>
<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>
</dd>
</dl>
</blockquote>

<p>
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
security checks on the file to be run. Please see the <a href="Use.htm">Use documentation</a>
for a complete description.
</p>

<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
<a href="http://www.libpng.org/pub/png/pngintro.html" 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
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
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>png16malpha</code> and <code>pngalpha</code> devices are 32-bit RGBA color with transparency
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. The devices differ, in that the <code>pngalpha</code> device
enables Text and graphics anti-aliasing by default. We now recommend that people use the <code>png16malpha</code>
device in preference, and achieve any required antialiasing via the <code>DownScaleFactor</code> parameter,
as this gives better results in many cases.</p>

<h4>Options</h4>

<p>The <code>pngmonod</code>, <code>png16m</code>, <code>pnggray</code>, <code>png16malpha</code> and
<code>pngalpha</code> devices all respond to the following:</p>

<blockquote>
<dl>
<dt><code>-dDownScaleFactor=</code><b><em>integer</em></b></dt>
<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:
<blockquote>
<pre>
 <kbd>gs -sDEVICE=png16m -r600 -dDownScaleFactor=3 -o tiger.png\
      examples/tiger.eps</kbd>
</pre>
</blockquote>
</dd>
</dl>
</blockquote>

<p>The <code>pngmonod</code> device responds to the following option:</p>

<blockquote>
<dl>
<dt><code>-dMinFeatureSize=</code><em>state</em> (0 to 4; default = 1)</dt>
<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>

<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>
</dl>
</blockquote>

<p>The <code>png16malpha</code> and <code>pngalpha</code> devices respond to the following option:</p>

<blockquote>
<dl>
<dt><code>-dBackgroundColor=</code><b><em>16#RRGGBB</em></b> (RGB color, default white = 16#ffffff)</dt>
<dd>For the <code>png16malpha</code> and <code>pngalpha</code> devices only,
set the suggested background color in the PNG bKGD chunk.
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
page.</dd>
</dl>
</blockquote>

<h4>Examples</h4>

<p>Examples of how to use Ghostscript to convert postscript to PNG image files:</p>

<blockquote>
<pre>
 <kbd>gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=png16m -dGraphicsAlphaBits=4 \
      -sOutputFile=tiger.png examples/tiger.png</kbd>

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

<p>In commercial builds, the <code>png16m</code> device will accept a <code>-dDeskew</code> option to automatically detect/correct skew when generating output bitmaps.</p>

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

<p>
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>

<p>Technically these produce <a href="http://www.ijg.org/">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>

<blockquote>
<a href="http://www.faqs.org/faqs/jpeg-faq/" class="offsite">http://www.faqs.org/faqs/jpeg-faq/</a>
</blockquote>

<h4>Examples</h4>

<p>
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>

<blockquote>
<pre><kbd>gs -sDEVICE=jpeg -sOutputFile=foo.jpg foo.ps</kbd></pre>
</blockquote>

<h4>Options</h4>

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

<blockquote>
<dl>
<dt><code>-dJPEGQ=</code><b><em>N</em></b> (integer from 0 to 100, default 75)</dt>
<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>
<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>
</dl>
</blockquote>

<p>
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.
</p>


<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
utility.</p>

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

<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="http://partners.adobe.com/asn/developer/pdfs/tn/TIFF6.pdf" class="offsite">TIFF 6.0 Specification</a>
published by Adobe Systems Incorporated.</p>
<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.
</p>
<p>
There are two unrelated sets of TIFF drivers.  There are five color TIFF
drivers that produce uncompressed output:</p>

<blockquote>
<dl>
<dt><code>tiffgray</code></dt>
<dd>Produces 8-bit gray output.</dd>
<dt><code>tiff12nc</code></dt>
<dd>Produces 12-bit RGB output (4 bits per component).</dd>
<dt><code>tiff24nc</code></dt>
<dd>Produces 24-bit RGB output (8 bits per component).</dd>
<dt><code>tiff48nc</code></dt>
<dd>Produces 48-bit RGB output (16 bits per component).</dd>
<dt><code>tiff32nc</code></dt>
<dd>Produces 32-bit CMYK output (8 bits per component).</dd>
<dt><code>tiff64nc</code></dt>
<dd>Produces 64-bit CMYK output (16 bits per component).</dd>
<dt><a name="tiffsep"></a><code>tiffsep</code></dt>
<dd>
The <code>tiffsep</code> device creates multiple output files: a single 32 bit
composite CMYK file and multiple tiffgray files, one for each
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.

<p>The default compression is <code>lzw</code> but this may be overridden by
the <code>-sCompression=</code> option.</p>

<p>
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
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>

<p>
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>
<p>Note that, while the name of the ink is case-sensitive, the filename may not be
(depending on the Operating System), so if a spot name matches one of the process
ink names, it will have the spot number included as part of the name (eg YELLOW0).
</p>

<p>
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
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>

<p>
The <code>tiffsep</code> device will automatically recognize spot colors. In this
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>

<p>
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>

<p>
If only a subset of the colorants for a file is desired, then the separations
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>

<p>
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>

<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
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>

<p>
Generally Ghostscript will support a maximum of 64 process and spot
colors.   The <code>tiffsep</code> device the <code>psdcmyk</code> device
and the <code>psdcmyk16</code> devices maintain rendered data
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
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>

<p>
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
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
colorants that you wish to be able to handle and must be no more than the 64 minus the
number of process colors. For example, 60 or less for a CMYK device such as tiffsep.
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
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>
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>

<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>
(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>

<p>In commercial builds, with 8 bit per component output, the <code>-dDeskew</code> option
can be used to automatically detect/correct skew when generating output bitmaps.</p>

<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>

</dd>
<dt><a name="tiffsep1"></a><code>tiffsep1</code></dt>
<dd>
The <code>tiffsep1</code> device creates multiple output files, one for each component
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.

<p>
The file specified via the OutputFile command line parameter will not be
created (it is opened, but deleted prior to finishing each page).</p>

<p>
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
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>
</dd>

<dt><a name="tiffscaled"></a><code>tiffscaled</code></dt>
<dd>
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
below.</dd>


<dt><a name="tiffscaled4"></a><code>tiffscaled4</code></dt>
<dd>
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
below.</dd>

<dt><a name="tiffscaled8"></a><code>tiffscaled8</code></dt>
<dd>
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>

<dt><a name="tiffscaled24"></a><code>tiffscaled24</code></dt>
<dd>
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.

<p>In commercial builds, the <code>-dDeskew</code> option can be used to automatically detect/correct skew when generating output bitmaps.</p>
</dd>
<dt><a name="tiffscaled32"></a><code>tiffscaled32</code></dt>
<dd>
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.

<p>In commercial builds, the <code>-dDeskew</code> option can be used to automatically detect/correct skew when generating output bitmaps.</p>
</dd>
</dl>
</blockquote>

<p>
The remaining TIFF drivers all produce black-and-white output with different
compression modes:</p>

<blockquote>
<dl>
<dt><code>tiffcrle</code></dt>
<dd>G3 fax encoding with no EOLs</dd>
<dt><code>tiffg3</code></dt>
<dd>G3 fax encoding with EOLs</dd>
<dt><code>tiffg32d</code></dt>
<dd>2-D G3 fax encoding</dd>
<dt><code>tiffg4</code></dt>
<dd>G4 fax encoding</dd>
<dt><code>tifflzw</code></dt>
<dd>LZW-compatible (tag = 5) compression</dd>
<dt><code>tiffpack</code></dt>
<dd>PackBits (tag = 32773) compression</dd>
</dl>
</blockquote>

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

<h4>Options</h4>

<p>
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>

<blockquote>
<dl>
<dt><code>-dMaxStripSize=<em>N</em></code> (non-negative integer; default = 8192)</dt>
<dd>Set the maximum (uncompressed) size of a strip.</dd>
</dl>
</blockquote>

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

<p>
If the value of the <code>MaxStripSize</code> parameter is smaller than a
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>

<p>
If the value of MaxStripSize is 0, then the entire image will be a single strip.</p>


<p>
Since v. 8.51 the logical order of bits within a byte, FillOrder, tag = 266 is
controlled by a parameter:</p>

<blockquote>
<dl>
<dt><code>-dFillOrder=<em>1 | 2 </em></code> (default = 1)</dt>
<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>
</dl></blockquote>

<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>

<p>
The writing of BigTIFF format output files is controlled with the
<code>-dUseBigTIFF</code> parameter.</p>
<p>
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>

<blockquote>
<dl>
<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>
</dl>
</blockquote>

<p>
The writing of the DateTime TAG can be controlled using the
<code>-dTIFFDateTime</code> parameter.</p>

<blockquote>
<dl>
<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>
</dl>
</blockquote>

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

<blockquote>
    <dl>
    <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>
    </dl>
</blockquote>

<p>
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>

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

<blockquote><dl>
<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>

<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
off.</dd>

<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>
<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>

<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>

<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>

</dl></blockquote>

<p>
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>

<blockquote><dl>
<dt><code>-dDownScaleFactor=<em>factor</em></code> (integer <= 8; default = 1)</dt>
<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
<code>-r600</code> and then specifying <code>-dDownScaleFactor=3</code> will produce
a 200dpi image.</dd>
</dl></blockquote>

<blockquote><dl>
<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.
<p>
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>
</dd>
</dl></blockquote>

<p>
The <code>tiffsep</code> TIFF device also provide this parameter:</p>

<blockquote><dl>
<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><dd></dd>
</dl></blockquote>

<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>

<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>

<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>

<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
example:</p>

<blockquote><code>
    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
</code></blockquote>

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

<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>

<h3><a name="fax"></a>FAX</h3>

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

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

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

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

<p>
BMP is a simple uncompressed image format commonly used on MS Windows.
It is supported by the devices <code>bmpmono bmpgray bmpsep1
   bmpsep8 bmp16 bmp256 bmp16m bmp32b</code>.
</p>

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

<p>
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>
series of devices.
</p>

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

<p>
PSD is the image format used by Adobe Photoshop.
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
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>
<p>
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.
</p>
<p>
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>

<p>
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>

<p>
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
result in an <code>ioerror</code> Postscript error.</p>

<p>In commercial builds, for the <code>psdcmyk</code> and <code>psdrgb</code> devices, the <code>-dDeskew</code> option can be used to automatically detect/correct skew when generating output bitmaps.</p>

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

<p>
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.
</p>
<p>
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).
</p>
<p>
There are five devices named pdfimage8, pdfimage24, pdfimage32, pclm and pclm8. 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
and the pclm8 device only supports 8-bit gray.
These are all implemented as 'downscale' devices, which means they can implement page level
anti-aliasing using the <code>-dDownScaleFactor</code> switch.
</p>

<blockquote>
<dl>
<dt><code>-dDownScaleFactor=</code><b><em>integer</em></b></dt>
<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>
<blockquote>
<pre>
 <kbd>gs -sDEVICE=pdfimage8 -r600 -dDownScaleFactor=3 -o tiger.pdf\
      examples/tiger.eps</kbd>
</pre>
</blockquote>
</blockquote>

<p>In commercial builds, the <code>-dDeskew</code> option can be used to automatically detect/correct skew when generating the output file.</p>

<p>
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.
</p>
<p>
For JPEG compression the devices support both the JPEGQ and QFactor switches as documented for the <a href="#JFIF">JPEG</a> file format device.
</p>
<p>
In addition, the PCLm device supports some other parameters. Firstly, the
<code>-dStripHeight</code> switch to set the vertical height
of the strips of image content, as required by the specification.
</p>
<p>Secondly, the standard postscript <code>-dDuplex</code> and
<code>-dTumble</code>switches are supported, in that if both are
set to true, every verso page (i.e. all even pages) will be
rotated by 180 degrees.</p>

<p>As an extension to this, a <code>-dTumble2</code> parameter is
also supported that will add an additional X-axis flip for every
verso page. Thus <code>-dDuplex=true -dTumble=false -dTumble2=true</code>
will result in verso pages being flipped horizontally, and
<code>-dDuplex=true -dTumble=true -dTumble2=true</code> will result
in verso pages being flipped vertically.</p>

<hr>

<p>
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>

<hr>

<h2><a name="OCR-Devices"></a>Optical Character Recognition (OCR) devices</h2>

<h3><a name="OCR"></a>OCR text output</h3>

<p>
  These devices render internally in 8 bit greyscale, and then
  feed the resultant image into an OCR engine. Currently, we
  are using the Tesseract engine. Not only is this both free
  and open source, it gives very good results, and supports
  a huge number of languages/scripts.
</p>
<p>
  The Tesseract engine relies on files to encapsulate each
  language and/or script. These &quot;traineddata&quot; files
  are available in different forms, including <a href="http://github.com/tesseract-ocr/tessdata_fast">fast</a>
  and <a href="http://github.com/tesseract-ocr/tessdata_best">best</a> variants.
  Alternatively, people can train their own data using the
  standard Tesseract tools.
</p>
<p>
  These files are looked for from a variety of places.
</p>
<ul>
  <li>Firstly, files will be searched for in the directory given by the
    environment variable TESSDATA_PREFIX.
  <li>Next, they will be searched for within the ROM filing system. Any
    files placed in &quot;tessdata&quot; will be included within the ROM
    filing system in the binary for any standard (COMPILE_INITS=1) build.
  <li>Next, files will be searched for in the configured 'tessdata' path. On
    Unix, this can be specified at the configure stage using
    '--with-tessdata=&lt;path&gt;' (where &lt;path&gt; is a list of
    directories to search, separated by ':' (on Unix) or ';' (on Windows)).
  <li>Finally, we resort to searching the current directory.
</ul>
<p>
  Please note, this pattern of directory searching differs from the original
  release of the OCR devices.
</p>
<p>
  By default, the OCR process defaults to looking for English text,
  using &quot;eng.traineddata&quot;. This can be changed by using the
  <code>-sOCRLanguage=</code> switch;
</p>
<blockquote>
<dl>
<dt><code>-sOCRLanguage=</code><b><em>language</em></b></dt>
<dd>This sets the trained data sets to use within the Tesseract
  OCR engine. For example, the following will use English and
  Arabic:</dd></dl>
<blockquote>
<pre>
 <kbd>gs -sDEVICE=ocr -r200 -sOCRLanguage="eng+ara" -o out.txt\
      zlib/zlib.3.pdf</kbd>
</pre>
</blockquote>
</blockquote>
<p>
  The first device is named ocr. It extracts data as unicode codepoints
  and outputs them to the device as a stream of UTF-8 bytes.
</p>
<p>
  The second device is named hocr. This extracts the data in
  <a href="wikipedia.org/wiki/HOCR">hOCR</a> format.
</p>
<p>
  These devices are implemented as downscaling devices, so the
  standard parameters can be used to control this process. It
  may seem strange to use downscaling on an image that is not
  actually going to be output, but there are actually good reasons
  for this. Firstly, the higher the resolution, the slower the
  OCR process. Secondly, the way the Tesseract OCR engine works
  means that anti-aliased images perform broadly as well as the
  super-sampled image from which it came.
</p>

<h3><a name="PDFocr"></a>PDF image output (with OCR text)</h3>

<p>
  These devices do the same render to bitmap and wrap as a PDF process as
  the <a name="PDFimage">PDFimage</a> devices above, but with the addition
  of an OCR step at the end. The OCR'd text is overlaid &quot;invisibly&quot;
  over the images, so searching and cut/paste should still work.
</p>
<p>
  The OCR engine being used is Tesseract. For information on this
  including how to control what language data is used, see the <a href="OCR">
  OCR devices</a> section above.
</p>
<p>
  There are three devices named pdfocr8, pdfocr24 and pdfocr32. These
  produce valid PDF files with a colour depth of 8 (Gray), 24 (RGB) or
  32 (CMYK).
</p>
<p>
  These devices accept all the same flags as the <a name="PDFimage">PDFimage</a>
  devices described above.
</p>
<p>

<h3><a name="PDFwriteocr"></a>Vector PDF output (with OCR Unicode CMaps)</h3>
<p>
The pdfwrite device has been augmented to use the OCR engine to analyse text
(not images!) in the input stream, and derive Unicode code points for it.
That information can then be used to create ToUnicode CMaps which are attached
to the Font (or CIDFont) objects embedded in the PDF file.
</p>
<p>
Fonts which have ToUnicode CMaps can be reliably (limited by the accuracy of
the CMap) used in search and copy/paste functions, as well as text extraction
from PDF files. Note that OCR is not a 100% perfect process; it is possible
that some text might be misidentified.
</p>
<p>
OCR is a slow operation! In addition it can (for Latin text at least) sometimes
be preferable not to add ToUnicode information which may be incorrect, but instead
to use the existing font Encoding. For English text this may give better results.
</p>
<p>For these reasons the OCR functionality of pdfwrite can be controlled by using a new
parameter <code>-sUseOCR</code>. This has three possible values;
</p>
<dl>
<dt><code>-sUseOCR=</code><b><em>string</em></b></dt>

    <dt>Never</dt><dd>Default - don't use OCR at all even if support is built-in.</dd>
    <dt>AsNeeded</dt><dd>If there is no existing ToUnicode information, use OCR.</dd>
    <dt>Always</dt><dd>Ignore any existing information and always use OCR.</dd>

</dl>
</p>

<hr>

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

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

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

<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>

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

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

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


<h3><a name="TXT"></a>Text output</h3>

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

<p>  Please refer to
<a href="VectorDevices.htm">VectorDevices.htm</a> for documentation on the
device options for these devices.
</p>

<hr>

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

<p>
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>

<p>
This section describes the various display-oriented devices that are available
in Ghostscript.</p>

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

<p>
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>

<p>
The available devices are:</p>

<dl>
<dt><b>x11</b></dt>
<dd>This is the default device, handling display on X11R6.</dd>

<dt><b>x11alpha</b></dt>
<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>

<dt><b>x11cmyk</b></dt>
<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>

<dt><b>x11mono</b></dt>
<dd>This is a strict black-and-white device for 1-bit monochrome displays.</dd>

<dt><b>x11gray2</b></dt>
<dd>This is a device for 2 bpp (4-level) monochrome displays.</dd>

<dt><b>x11gray4</b></dt>
<dd>This is a device for 4 bpp (16-level) monochrome displays.</dd>
</dl>

<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>

<blockquote><code>
defaults write org.x.X11 depth 24
</code></blockquote>

<h3><a name="display_device"></a>display device (MS Windows, OS/2, gtk+)</h3>
<p>
The <code>display</code> device is used by the MS Windows,
OS/2 and the gtk+ versions of ghostscript.
</p>

<h4>Options</h4>

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

<blockquote>
<dl>
<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.
<p>
The bit fields are:
</p>
<ul>
<li> native (1), gray (2), RGB (4), CMYK (8), or separation (80000)
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>
</ul>
<p>For more details, see the <a href="API.htm#display">Ghostscript
Interpreter API.</a></p>
</dd>
<dt><code>-dDisplayResolution=</code><b><em>DPI</em></b></dt>
<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
<code>-r<em>DPI</em></code>.</dd>
</dl>

</blockquote>

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

<blockquote>
<dl>
<dt><code>SeparationColorNames</code></dt>
<dd>An array giving the names of the spot colors</dd>

<dt><code>SeparationOrder</code></dt>
<dd>An array giving the names and order of the colorants
    to be output.</dd>
</dl>
</blockquote>


<hr>

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

<p>
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>

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

<p>
A typical command line for IJS is:
</p>

<blockquote>
<code>
gs -dSAFER -sDEVICE=ijs -sIjsServer=hpijs
 -sDeviceManufacturer=HEWLETT-PACKARD -sDeviceModel='DESKJET 990'
 -dIjsUseOutputFD -sOutputFile=/dev/usb/lp1 -dNOPAUSE --
 examples/tiger.eps
</code>
</blockquote>


<p>
Individual IJS command line parameters are as follows:
</p>

<dl>
<dt><code>-sIjsServer=</code><em>{path}</em></dt>
<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>
</dl>

<dl>
<dt><code>-sDeviceManufacturer=</code><em>{name}</em></dt>
<dt><code>-sDeviceModel=</code><em>{name}</em></dt>
<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>
</dl>

<dl>
<dt><code>-sIjsParams=</code><em>{params}</em></dt>
<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>
</dl>

<dl>
<dt><code>-dIjsUseOutputFD</code></dt>
<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>
</dl>

<dl>
<dt><code>-dBitsPerSample=</code><em>N</em></dt>
<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>
</dl>

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

<dl>
<dt><code>-r</code><em>number</em></dt>
<dt><code>-r</code><em>number1</em><code>x</code><em>number2</em></dt>
<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>
</dl>

<dl>
<dt><code>-dDuplex</code></dt>
<dt><code>-dTumble</code></dt>
<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
bottom.</dd>
</dl>

<dl>
<dt><code>-sProcessColorModel=</code><em>{name}</em></dt>
<dd>Use this flag to select the process color model. Suitable values
include DeviceGray, DeviceRGB, and DeviceCMYK.</dd>
</dl>

<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>

<blockquote>
DEVICE_DEVS2=&#36;(DD)ijs.dev
</blockquote>

<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>

<blockquote>
IJSSRCDIR=ijs
IJSEXECTYPE=unix
</blockquote>

<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>

<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>

<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
to support new drivers!</p>
<hr>
<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>

<blockquote>
DEVICE_DEVS2=&#36;(DD)rinkj.dev
</blockquote>

<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>

<blockquote><code>
gs -r1440x720 -sDEVICE=rinkj -sOutputFile=/dev/usb/lp0
  -sSetupFile=lib/rinkj-2200-setup -sProfileOut=2200-cmyk.icm
  -dNOPAUSE -dBATCH file.ps
</code></blockquote>

<p>
Individual Rinkj command line parameters are as follows:
</p>

<dl>
<dt><code>-sSetupFile=</code><em>{path}</em></dt>
<dd>Specifies the path for the setup file.</dd>

<dt><code>-sProfileOut=</code><em>{path}</em></dt>
<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>
</dl>

<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
are:</p>

<dl>
<dt><code>Manufacturer:</code><em>{name}</em></dt>
<dt><code>Model:</code><em>{name}</em></dt>
<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>

<dt><code>Resolution:</code><em>{x-dpi}</em>x<em>{y-dpi}</em></dt>
<dd>The resolution in dpi. Usually, this should match the
Ghostscript resolution set with the <code>-r</code> switch. Otherwise,
the page image will be scaled.</dd>

<dt><code>Dither:</code><em>{int}</em></dt>
<dd>Selects among variant dither options. Currently, the choices are
<code>1</code> for one-bit dither, and <code>2</code>, for a 2-bit variable
dot dither.</dd>

<dt><code>Aspect:</code><em>{int}</em></dt>
<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>

<dt><code>Microdot:</code><em>{int}</em></dt>
<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>

<dt><code>Unidirectional:</code><em>{int}</em></dt>
<dd>Enables (1) or disables (0) unidirectional printing, which is
slower but possibly higher quality.</dd>

<dt><code>AddLut:</code><em>{plane}</em></dt>
<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>
</dl>

<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>

<p>A known issue with this driver is poor support for margins and
page size. In some cases, this will cause an additional page to be
ejected at the end of a job. You may be able to work around this by
supplying a cut-down value for <code>-dDEVICEHEIGHTPOINTS</code>, for
example 755 for an 8.5x11 inch page on the EPSON 2200.</p>
<hr>
<h2><a name="HP_ijs"></a>HP Deskjet official drivers</h2>

<p>
HP provides official drivers for many of their Deskjet printer models.
In order to use these drivers, you will need the HP Inkjet Server as
well as Ghostscript, available from <a
href="http://hpinkjet.sourceforge.net">http://hpinkjet.sourceforge.net</a>.
This version of Ghostscript includes the patch from version 0.97 of
the hpijs software. If you are installing hpijs from an RPM, you will
only need the hpijs RPM, not the Ghostscript-hpijs one, as the code
needed to work with hpijs is already included.</p>

<p>
Note that newer version of the hpijs drivers support the IJS protocol.
If you can, you should consider using the ijs driver instead. Among
other things, the hpijs Ghostscript driver is Unix-only, and is untested
on older Unix platforms.</p>

<p>
As of the 0.97 version, hpijs supports the following printer models:</p>

<dl><dt><b>e-Series:</b></dt>
<dd>e-20</dd>
<dt><b>DeskJet 350C Series:</b></dt>
<dd>350C</dd>
<dt><b>DeskJet 600C Series:</b></dt>
<dd>600C, 660C, 670/672C, 670TV, 680/682C</dd>
<dt><b>DeskJet 600C Series Photo:</b></dt>
<dd>610/612C, 640/648C, 690/692/693/694/695/697C</dd>
<dt><b>DeskJet 630C Series:</b></dt>
<dd>630/632C</dd>
<dt><b>DeskJet 800C Series:</b></dt>
<dd>810/812C, 830/832C, 840/842/843C, 880/882C, 895C</dd>
<dt><b>DeskJet 900C Series, PhotoSmart::</b></dt>
<dd>930/932C, 950/952C, 970C, PhotoSmart 1000/1100</dd>
<dt><b>DeskJet 990C, PhotoSmart:</b></dt>
<dd>960C, 980C, 990C, PhotoSmart 1215/1218</dd>

</dl>

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

<blockquote>
DEVICE_DEVS2=&#36;(DD)DJ630.dev &#36;(DD)DJ6xx.dev &#36;(DD)DJ6xxP.dev &#36;(DD)DJ8xx.dev &#36;(DD)DJ9xx.dev &#36;(DD)DJ9xxVIP.dev &#36;(DD)AP21xx.dev
</blockquote>

<p>
Please see <a
href="http://hpinkjet.sourceforge.net">http://hpinkjet.sourceforge.net</a>
for more information about this driver. Thanks to the folks at HP,
especially David Suffield for making this driver available and working to
integrate it with Ghostscript.
</p>
<hr>
<h2><a name="gimp-print"></a>Gimp-Print driver collection</h2>

<p>
The Gimp-Print project provides a large collection of printer drivers
with an IJS interface. Please see their
<a href="http://gimp-print.sourceforge.net/" class="offsite">website</a>
for details.
</p>

<hr>
<h2><a name="Win"></a>MS Windows printers</h2>

<p>
This section was written by Russell Lang, the author of Ghostscript's
MS&nbsp;Windows-specific printer driver, and updated by
<a href="mailto:Pierre.Arnaud@opac.ch">Pierre Arnaud</a>,
the current maintainer.
</p>

<p>
The <code>mswinpr2</code> device uses MS&nbsp;Windows printer drivers, and
thus should work with any printer with device-independent bitmap (DIB)
raster capabilities. The printer resolution cannot be selected directly
using PostScript commands from Ghostscript: use the printer setup in the
Control Panel instead. It is however possible to specify a maximum resolution
for the printed document (see below).
</p>

<p>
If no Windows printer name is specified in <code>-sOutputFile</code>,
Ghostscript prompts for a Windows printer using the standard Print Setup
dialog box.  You must set the orientation to Portrait and the page size to
that expected by Ghostscript; otherwise the image will be clipped.
Ghostscript sets the physical device size to that of the Windows printer
driver, but it does not update the PostScript clipping path.
</p>

<p>
If a Windows printer name is specified in <code>-sOutputFile</code> using
the format <code>"%printer%printer_name"</code>, for instance
</p>

<blockquote><code>
gs ... -sOutputFile="%printer%Apple LaserWriter II NT"
</code></blockquote>

<p>
then Ghostscript attempts to open the Windows printer without prompting
(except, of course, if the printer is connected to <code>FILE:</code>).
Ghostscript attempts to set the Windows printer page size and orientation
to match that expected by Ghostscript, but doesn't always succeed.  It uses
this algorithm:
</p>

<ol>
<li>If the requested page size matches one of the Windows standard page
sizes +/- 2mm, request that standard size.</li>

<li>Otherwise if the requested page size matches one of the Windows
standard page sizes in landscape mode, ask for that standard size in
landscape.</li>

<li>Otherwise ask for the page size by specifying only its dimensions.</li>

<li>Merge the requests above with the defaults.  If the printer driver
ignores the requested paper size, no error is generated: it will print on
the wrong paper size.</li>

<li>Open the Windows printer with the merged orientation and size.</li>
</ol>

<p>
The Ghostscript physical device size is updated to match the Windows
printer physical device.
</p>

<h3><a name="Win_properties"></a>Supported command-line parameters</h3>

<p>
The <code>mswinpr2</code> device supports a limited number of command-line
parameters (e.g. it does not support setting the printer resolution). The
recognized parameters are the following:
</p>

<blockquote>
<dl>
<dt><code>-sDEVICE=mswinpr2</code></dt>
<dd>Selects the MS&nbsp;Windows printer device. If Ghostscript was not
compiled with this device as the default output device, you have to specify
it on the command line.</dd>

<dt><code>-dNoCancel</code></dt>
<dd>Hides the progress dialog, which shows the percent of the document page
already processed and also provides a <em>cancel</em> button. This option
is useful if GS is intended to print pages in the background, without any
user intervention.</dd>

<dt><code>-sOutputFile=</code><b>"%printer%<em>printer_name</em>"</b></dt>
<dd>Specifies which printer should be used. The <em>printer_name</em> should be
typed exactly as it appears in the Printers control panel, including spaces.</dd>

</dl>
</blockquote>

<h3><a name="Win_options"></a>Supported options (device properties)</h3>

<p>
Several extra options exist which cannot be set through the command-line,
but only by executing the appropriate PostScript setup code. These options
can be set through the inclusion of a setup file on the command-line:
</p>

<blockquote><code>
gs ... setup.ps ...
</code></blockquote>

<p>
The <code>setup.ps</code> file is responsible for the device selection, therefore
you should not specify the <code>-sDEVICE=mswinpr2</code> option on the
command-line if you are using such a setup file. Here is an example of such
a setup file:
</p>

<blockquote><pre>
mark
  /NoCancel      true                       % don't show the cancel dialog
  /BitsPerPixel  4                          % force 4 bits/pixel
  /UserSettings
    &lt;&lt;
      /DocumentName  (Ghostscript document) % name for the Windows spooler
      /MaxResolution 360                    % maximum document resolution
    &gt;&gt;
  (mswinpr2) finddevice                     % select the Windows device driver
  putdeviceprops
setdevice
</pre></blockquote>

<p>
This example disables the progress dialog (same as the <code>-dNoCancel</code>
option), forces a 4 bits/pixel output resolution and specifies additional user
settings, such as the document name (which will be displayed by the Windows
spooler for the queued document) and the maximum resolution (here 360&nbsp;dpi).
It then finds and selects an instance of the MS&nbsp;Windows device printer
and activates it. This will show the standard printer dialog, since no
<code>/OutputFile</code> property was specified.
</p>

<p>
The following options are available:
</p>

<blockquote>
<dl>
<dt><code>/NoCancel <em>boolean</em></code></dt>
<dd>Disables (hides) the progress dialog when set to <em><code>true</code></em> or
show the progress dialog if not set or set to <em><code>false</code></em>.</dd>

<dt><code>/OutputFile <em>string</em></code></dt>
<dd>Specifies which printer should be used. The string should be of the form
<code>%printer%<em>printer_name</em></code>, where the <em>printer_name</em> should be
typed exactly as it appears in the Printers control panel, including spaces.</dd>

<dt><code>/QueryUser <em>integer</em></code></dt>
<dd>Shows the standard printer dialog (<code>1</code> or any other value),
shows the <em>printer setup dialog</em> (<code>2</code>) or selects the
<em>default Windows printer</em> without any user interaction (<code>3</code>).</dd>

<dt><code>/BitsPerPixel <em>integer</em></code></dt>
<dd>Sets the device depth to the specified bits per pixel. Currently supported
values are <code>1</code> (monochrome), <code>4</code> (CMYK with screening
handled by Ghostscript) and <code>24</code> (True Color, dithering handled by
the Windows printer driver; this option can produce huge print jobs).</dd>

<dt><code>/UserSettings <em>dict</em></code></dt>
<dd>Sets additional options, defined in a dictionary. The following properties can
be set:</dd>


<dt><code>/DocumentName <em>string</em></code></dt>
<dd>Defines the user friendly document name which will be displayed by the
Windows spooler.</dd>

<dt><code>/DocumentRange <em>[n1 n2]</em></code></dt>
<dd>Defines the range of pages contained in the document. This information can
be used by the printer dialog, in conjunction with the following property.</dd>

<dt><code>/SelectedRange <em>[n1 n2]</em></code></dt>
<dd>Defines the selected range of pages. This information will be displayed in
the printer dialog and will be updated after the user interaction. A PostScript
program could check these values and print only the selected page range.</dd>

<dt><code>/MaxResolution <em>dpi</em></code></dt>
<dd>Specifies the maximum tolerated output resolution. If the selected printer has
a higher resolution than <code>dpi</code>, then Ghostscript will render the
document with a submultiple of the printer resolution. For example, if
<code>MaxResolution</code> is set to 360 and the output printer supports
up to 1200 dpi, then Ghostscript renders the document with an internal
resolution of 1200/4=300 dpi. This can be very useful to reduce the memory
requirements when printing in True Color on some high resolution ink-jet color
printers.</dd>


</dl>
</blockquote>

<p>
These properties can be queried through the <code>currentpagedevice</code>
operator. The following PostScript code snippet shows how to do it for some
of the properties:
</p>

<blockquote><pre>
currentpagedevice /BitsPerPixel get ==  % displays the selected depth

currentpagedevice /UserSettings get     % get the additional options..
/us exch def                            % ..and assign them to a variable

us /DocumentName get ==     % displays the document name
us /SelectedRange get ==    % displays the selected page range

% other misc. information (don't rely on them)

us /Color get ==            % 1 =&gt; monochrome output, 2 =&gt; color output
us /PrintCopies get ==      % displays the number of copies requested
</pre></blockquote>

<p>
There are a few undocumented parameters stored in the <code>UserSettings</code>
dictionary. You should not rely on them. Their use is still experimental and
they could be removed in a future version.
</p>

<h3><a name="Win_duplex"></a>Duplex printing</h3>

<p>
If the Windows printer supports the duplex printing feature, then it will
also be available through the <code>mswinpr2</code> device. You can query
for this support through the <code>/Duplex</code> property of the
<code>currentpagedevice</code>. If it returns <code>null</code>, then
the feature is not supported by the selected printer. Otherwise, <code>true</code>
means that the printer is currently set up to print on both faces of the paper
and <code>false</code> that it is not, but that it can.
</p>

<p>
The following example shows how to print on both faces of the paper (using
the long side of the paper as the reference):
</p>

<blockquote><pre>
&lt;&lt; /Duplex true /Tumble false &gt;&gt; setpagedevice
</pre></blockquote>

<hr>

<h2><a name="SPARCprinter"></a>Sun SPARCprinter</h2>

<p>
This section was contributed by Martin Schulte.</p>

<p>
With a SPARCprinter you always buy software that enables you to do
PostScript printing on it.  A page image is composed on the host, which
sends a bitmap to the SPARCprinter through a special SBUS video interface.
So the need for a Ghostscript interface to the SPARCPrinter seems low, but
on the other hand, Sun's software prints some PostScript drawings
incorrectly: some pages contain a thin vertical line of rubbish, and on
some Mathematica drawings the text at the axes isn't rotated.  Ghostscript,
however, gives the correct results.  Moreover, replacing proprietary
software should never be a bad idea.</p>

<p>
The problem is that there has yet been no effort to make the SPARCPrinter
driver behave like a BSD output filter.  I made my tests using the script
shown here.</p>

<h3><a name="SPARC_install"></a>Installation</h3>

<p>
Add <code>sparc.dev</code> to <code>DEVICE_DEVS</code> and compile
Ghostscript as described in the documentation on <a href="Make.htm">how to
build Ghostscript</a>.  Afterwards you can use the following script as an
example for printing after modifying it with the right pathnames --
including for <b>{GSPATH}</b> the full pathname of the Ghostscript
executable:</p>

<blockquote>
<pre>outcmd1='/vol/local/lib/troff2/psxlate -r'
outcmd2='<b><em>{GSPATH}</em></b> -sDEVICE=sparc -sOUTPUTFILE=/dev/lpvi0 -'

if [ &#36;# -eq 0 ]
then
  &#36;outcmd1 | &#36;outcmd2
else
  cat &#36;* | &#36;outcmd1 | &#36;outcmd2
fi
</pre></blockquote>

<h3><a name="SPARC_problems"></a>Problems</h3>

<p>
Since <code>/dev/lpi</code> can be opened only for exclusive use, if
another job has it open (engine_ctl_sparc or another Ghostscript are the
most likely candidates), Ghostscript stops with "Error: /invalidfileaccess
in --.outputpage--"</p>

<p>
In case of common printer problems like being out of paper, a warning
describing the reason is printed to stdout.  The driver tries access again
each five seconds.  Due to a problem with the device driver (in the kernel)
the reason for printer failure isn't always reported correctly to the
program.  This is the case, for instance, if you open the top cover (error
E5 on the printer's display).  Look at the display on the printer itself if
a "Printer problem with unknown reason" is reported.  Fatal errors cause
the print job to be terminated.</p>

<p>
Note: there is some confusion whether the resolution setting should be
the integers 300 and 400, or the symbolic constants DPI300 and DPI400
(defined in lpviio.h). Ghostscript releases have had it both ways. It
is currently the latter. However, INOUE Namihiko reports (in bug
<a href="http://bugs.ghostscript.com/show_bug.cgi?id=215256"
class="offsite">#215256</a>)
that the former works better for him. If anyone
has a definitive answer, please let us know.</p>

<hr>

<h2><a name="Apple"></a>Apple dot matrix printer</h2>

<p>
This section was contributed by Mark Wedel
&lt;<a href="mailto:master@cats.ucsc.edu">master@cats.ucsc.edu</a>&gt;.</p>

<p>
The Apple Dot Matrix Printer (DMP) was a parallel predecessor to the
Imagewriter printer.  As far as I know, Imagewriter commands are a superset
of the Dot Matrix printer's, so the driver should generate output that can
be printed on Imagewriters.</p>

<p>
To print images, the driver sets the printer for unidirectional printing
and 15 characters per inch (cpi), or 120dpi.  It sets the line feed to 1/9
inch.  When finished, it sets the printer to bidirectional printing,
1/8-inch line feeds, and 12 cpi.  There appears to be no way to reset the
printer to initial values.</p>

<p>
This code does not set for 8-bit characters (which is required).  It also
assumes that carriage return-newline is needed, and not just carriage
return.  These are all switch settings on the DMP, and I have configured
them for 8-bit data and carriage return exclusively.  Ensure that the Unix
printer daemon handles 8-bit (binary) data properly; in my SunOS 4.1.1
<code>printcap</code> file the string "<code>ms=pass8,-opost</code>"
works fine for this.</p>

<p>
Finally, you can search <code>devdemp.c</code> for
"<code>Init</code>" and "<code>Reset</code>" to find the strings that
initialize the printer and reset things when finished, and change them to
meet your needs.</p>

<hr>

<h2><a name="Test"></a>Special and Test devices</h2>

<p>
The devices in this section are intended primarily for testing. They may
be interesting as code examples, as well.</p>

<h3><a name="Bit"></a>Raw 'bit' devices</h3>

<p>There are a collection of 'bit' devices that don't do any special formatting
but output 'raw' binary data for the page images. These are used for benchmarking
but can also be useful when you want to directly access the raster data.</p>

<p>
The raw devices are <code>bit bitrgb bitcmyk</code>.</p>

<h3><a name="Bounding_box_output"></a>Bounding box output</h3>

<p>
There is a special <code>bbox</code> "device" that just prints the
bounding box of each page.  You select it in the usual way:</p>

<blockquote><code>
gs -dSAFER -dNOPAUSE -dBATCH -sDEVICE=bbox
</code></blockquote>

<p>
It prints the output in a format like this:</p>

<blockquote>
<pre><code>%%BoundingBox: 14 37 570 719
%%HiResBoundingBox: 14.3ep08066 37.547999 569.495061 718.319158
</code></pre></blockquote>

<p>
Currently, it always prints the bounding box on <code>stderr</code>;
eventually, it should also recognize <code>-sOutputFile=</code>.</p>

<p>
By default, white objects don't contribute to the bounding box because
many files fill the whole page with white before drawing other objects.
This can be changed by:</p>

<blockquote><code>
&lt;&lt; /WhiteIsOpaque true &gt;&gt; setpagedevice
</code></blockquote>

<p>
Note that this device, like other devices, has a resolution and a (maximum)
page size.  As for other devices, the product (resolution x page size) is
limited to approximately 500K pixels.  By default, the resolution is 4000
DPI and the maximum page size is approximately 125", or approximately 9000
default (1/72") user coordinate units.  If you need to measure larger pages
than this, you must reset <em>both</em> the resolution and the page size in
pixels, e.g.,</p>

<blockquote><code>
gs -dNOPAUSE -dBATCH -sDEVICE=bbox -r100 -g500000x500000
</code></blockquote>

<h3><a name="Ink_coverage_output"></a>Ink coverage output</h3>

<p>
There are two special <code>inkcov</code> devices that print the
ink coverage of each page; the inkcov device and the ink_cov device.
They are selected like this:</p>

<blockquote><pre><code>
gs -dSAFER -dNOPAUSE -dBATCH -o- -sDEVICE=inkcov Y.pdf
gs -dSAFER -dNOPAUSE -dBATCH -o- -sDEVICE=ink_cov Y.pdf
</code></pre></blockquote>

<p>These commands also work as expected:</p>

<blockquote><pre><code>
gs -o X_inkcov.txt -sDEVICE=inkcov Y.pdf
gs -o X_inkcov_page%03d.txt -sDEVICE=inkcov Y.pdf
</code></pre></blockquote>

<p>
The devices print their output in a format like this:</p>

<blockquote>
<pre><code>Page 1
 0.10022  0.09563  0.10071  0.06259 CMYK OK
Page 2
 0.06108  0.05000  0.05834  0.04727 CMYK OK
</code></pre></blockquote>

<p>
The difference between the two devices is that the inkcov device considers each rendered pixel and whether
it marks the C, M, Y or K channels. So the percentages are a measure of how many device pixels
contain that ink. The ink_cov device gives the more traditional use of ink coverage, it
also considers the amount of each colourant at each rendered pixel, so the percentages in this
case are what percentage of the ink is used on the page.
</p>
<p>
As an example, If we take a page which is covered by a pure 100% cyan fill both devices would give
the same result 1.00 0.00 0.00 0.00; each pixel is marked by the cyan ink and each pixel contains 100% cyan.
If however we use a 50% cyan fill the inkcov device will still give 1.00 0.00 0.00 0.00 as 100% of the pixels contain cyan. The
ink_cov device, however, would give a result of 0.50 0.00 0.00 0.00.
</p>

<h3><a name="Permute"></a>Permutation (DeviceN color model)</h3>

<p>
With no additional parameters, the device named "permute" looks
to Ghostscript like a standard CMYK contone device, and outputs a
PPM file, using a simple CMYK-&gt;RGB transform. This should be the
baseline for regression testing.</p>

<p>
With the addition of <code>-dPermute=1</code>, the internal behavior changes
somewhat, but in most cases the resulting rendered file should be the
same. In this mode, the color model becomes "DeviceN" rather than
"DeviceCMYK", the number of components goes to six, and the color
model is considered to be the (yellow, cyan, cyan, magenta, 0, black)
tuple. This is what's rendered into the memory buffer. Finally, on
conversion to RGB for output, the colors are permuted back.</p>

<p>
As such, this code should check that all imaging code paths are
64-bit clean. Additionally, it should find incorrect code that assumes
that the color model is one of DeviceGray, DeviceRGB, or DeviceCMYK.</p>

<p>
Currently, the code has the limitation of 8-bit continuous tone
rendering only. An enhancement to do halftones is planned as well. Note,
however, that when testing permuted halftones for consistency, it is
important to permute the planes of the default halftone accordingly, and
that any file which sets halftones explicitly will fail a consistency
check.</p>

<h3><a name="SPOT"></a>spotcmyk (DeviceN color model)</h3>

<p>
The <code>spotcmyk</code> device was created for debugging and testing of the DeviceN
extensions to Ghostscript that were released in version 8.0.
There are also another device (<code>devicen</code>) in the same
source file.  It were created for testing however it are not actually useful
except as example code.</p>

<p>The <code>spotcmyk</code> device was also designed to provide example code for a
device which supports spot colors.
Spot colors need to be specified prior to opening the
first page.
This can be done via adding the
following to the command line: <code>-c "&lt;&lt; /SeparationColorNames [ /Name1 /Name2 ]
&gt;&gt; setpagedevice" -f</code>.</p>

<p>
The <code>spotcmyk</code> device produces a binary data file (similar to the bitcmyk
device) for the CMYK data.  This data file has the name specified by the "OutputFile"
parameter.
The device also produces a binary data file (similar to the bitmono device)
for each spot color plane.
These data files have the name specified by the "OutputFile"
parameter with "sn" appended to the end (where "n" is the spot color number 0 to 12)".</p>

<p>
After the <code>spotcmyk</code> device produces the binary data files, the files are read
and PCX format versions of these files are created with ".pcx" appended to the binary
source file name.</p>

<p> If the the <code>spotcmyk</code> is being used with three spot colors and the
"OutputFile" parameter is <code>xxx</code> then the following files would be created
by the device:</p>

<blockquote>
<pre>xxx - binary CMYK data
xxxs0 - binary data for first spot color
xxxs1 - binary data for second spot color
xxxs2 - binary data for third spot color
xxx.pcx - CMYK data in PCX format
xxxs0.pcx - first spot color in PCX format
xxxs1.pcx - second spot color in PCX format
xxxs2.pcx - third spot color in PCX format
</pre>
</blockquote>

<p>
The <code>spotcmyk</code> device has the creation of the binary data files separated
from the creation of the PCX files since the source file is intended as example
code and many people may not be interested in the PCX format. The PCX format was
chosen because it was simple to implement from preexisting code and viewers are
available.  The PCX format does have the disadvantage that most of those viewers
are on Windows.</p>


<h3><a name="XCF"></a>XCF (DeviceN color model)</h3>

<p>
The XCF file format is the native image format for the GIMP program. This format
is currently supported by two devices: <code> xcfrgb</code> and <code>xcfcmyk</code>.</p>

<blockquote><em>
We have been warned by the people supporting the GIMP program that they reserve
the right to change the
XCF format at anytime and thus these devices may become invalid. They are being
included in the documentation because we have received some questions about
these devices do.
</em></blockquote>

<p>
The XCF devices were created for testing of the DeviceN extensions to Ghostscript
which were released in version 8.0.</p>

<p>
The <code>xcfrgb</code> device uses a DeviceRGB process color model and creates
a normal XCF file.</p>

<p>
The <code>xcfcmyk</code> device was created as a means of viewing spot colors for
those users that do not have access to either Photoshop <a href="#PSD">(see the PSD
devices)</a> or a PCX viewer <a href="#SPOT">(see the <code>spotcmyk</code>
device)</a>.</p>

<p>
The <code>xcfcmyk</code> device starts by using a DeviceCMYK process color model. The
DeviceCMYK process color model allows the <code>xcfcmyk</code> device to also
support spot colors. Spot colors need to be specified prior to opening the
first page.
This can be done via adding the
following to the command line: <code>-c "&lt;&lt; /SeparationColorNames [ /Name1 /Name2 ]
&gt;&gt; setpagedevice" -f</code>.</p>

<p>
After a page is complete, the <code>xcfcmyk</code> converts the CMYK image data into
RGB for storing in the XCF output file.  The XCF format does not currently
support CMYK data directly. The spot color planes are converted into alpha
channel planes. This is done because the XCF format does not currently support
spot colors.</p>

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<p>
<small>Copyright &copy; 2000-2022 Artifex Software, Inc.  All rights reserved.</small>

<p>
This software is provided AS-IS with no warranty, either express or
implied.

This software is distributed under license and may not be copied, modified
or distributed except as expressly authorized under the terms of that
license.  Refer to licensing information at <a href="https://www.artifex.com">https://www.artifex.com</a>
or contact Artifex Software, Inc.,  1305 Grant Avenue - Suite 200,
Novato, CA 94945, U.S.A., +1(415)492-9861, for further information.

<p>
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