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<section id="tiffdither">
<h1>tiffdither<a class="headerlink" href="#tiffdither" title="Permalink to this heading">¶</a></h1>
<section id="synopsis">
<h2>Synopsis<a class="headerlink" href="#synopsis" title="Permalink to this heading">¶</a></h2>
<p><strong>tiffdither</strong> [ <em>options</em> ] <em>input.tif</em> <em>output.tif</em></p>
</section>
<section id="description">
<h2>Description<a class="headerlink" href="#description" title="Permalink to this heading">¶</a></h2>
<p><strong class="program">tiffdither</strong> converts a single channel 8-bit greyscale image to a bilevel image
using Floyd-Steinberg error propagation with thresholding.</p>
</section>
<section id="options">
<h2>Options<a class="headerlink" href="#options" title="Permalink to this heading">¶</a></h2>
<dl class="std option">
<dt class="sig sig-object std" id="cmdoption-tiffdither-c">
<span class="sig-name descname"><span class="pre">-c</span></span><span class="sig-prename descclassname"> <span class="pre">compress</span></span><a class="headerlink" href="#cmdoption-tiffdither-c" title="Permalink to this definition">¶</a></dt>
<dd><p>Specify the compression to use for data written to the output file:</p>
<table class="docutils align-default">
<thead>
<tr class="row-odd"><th class="head"><p>Compression</p></th>
<th class="head"><p>Description</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><p>none</p></td>
<td><p>no compression</p></td>
</tr>
<tr class="row-odd"><td><p>packbits</p></td>
<td><p>PackBits compression</p></td>
</tr>
<tr class="row-even"><td><p>lzw</p></td>
<td><p>Lempel-Ziv & Welch compression</p></td>
</tr>
<tr class="row-odd"><td><p>zip</p></td>
<td><p>Deflate compression</p></td>
</tr>
<tr class="row-even"><td><p>g3</p></td>
<td><p>CCITT Group 3 (T.4) compression</p></td>
</tr>
<tr class="row-odd"><td><p>g4</p></td>
<td><p>for CCITT Group 4 (T.6) compression</p></td>
</tr>
</tbody>
</table>
<p>By default <strong class="program">tiffdither</strong>
will compress data according to the value of the
<code class="docutils literal notranslate"><span class="pre">Compression</span></code> tag found in the source file.</p>
<p>The CCITT Group 3 and Group 4 compression algorithms can only
be used with bilevel data.</p>
<p>Group 3 compression can be specified together with several
T.4-specific options:
<code class="docutils literal notranslate"><span class="pre">1d</span></code> for 1-dimensional encoding,
<code class="docutils literal notranslate"><span class="pre">2d</span></code> for 2-dimensional encoding, and
<code class="docutils literal notranslate"><span class="pre">fill</span></code> to force each encoded scanline to be zero-filled so that the
terminating EOL code lies on a byte boundary.
Group 3-specific options are specified by appending a <code class="docutils literal notranslate"><span class="pre">:</span></code>-separated
list to the <code class="docutils literal notranslate"><span class="pre">g3</span></code> option; e.g. <code class="docutils literal notranslate"><span class="pre">-c</span> <span class="pre">g3:2d:fill</span></code>
to get 2D-encoded data with byte-aligned EOL codes.</p>
<p>LZW compression can be specified together with a <code class="docutils literal notranslate"><span class="pre">predictor</span></code> value.
A predictor value of 2 causes each scanline of the output image to undergo
horizontal differencing before it is encoded; a value
of 1 forces each scanline to be encoded without differencing.
LZW-specific options are specified by appending a <code class="docutils literal notranslate"><span class="pre">:</span></code>-separated
list to the <code class="docutils literal notranslate"><span class="pre">lzw</span></code> option; e.g. <code class="docutils literal notranslate"><span class="pre">-c</span> <span class="pre">lzw:2</span></code> for LZW
compression with horizontal differencing.</p>
</dd></dl>
<dl class="std option">
<dt class="sig sig-object std" id="cmdoption-tiffdither-f">
<span class="sig-name descname"><span class="pre">-f</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-tiffdither-f" title="Permalink to this definition">¶</a></dt>
<dd><p>Specify the bit fill order to use in writing output data.
By default, <strong class="program">tiffdither</strong>
will create a new file with the same fill order as the original.
Specifying
<strong class="command">-f lsb2msb</strong> will force data to be written with the
<code class="docutils literal notranslate"><span class="pre">FillOrder</span></code> tag set to <code class="docutils literal notranslate"><span class="pre">LSB2MSB</span></code>, while
<strong class="command">-f msb2lsb</strong> will force data to be written with the
<code class="docutils literal notranslate"><span class="pre">FillOrder</span></code> tag set to <code class="docutils literal notranslate"><span class="pre">MSB2LSB</span></code>.</p>
</dd></dl>
<dl class="std option">
<dt class="sig sig-object std" id="cmdoption-tiffdither-r">
<span class="sig-name descname"><span class="pre">-r</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-tiffdither-r" title="Permalink to this definition">¶</a></dt>
<dd><p>Make each strip have no more than the given number of rows.</p>
</dd></dl>
<dl class="std option">
<dt class="sig sig-object std" id="cmdoption-tiffdither-t">
<span class="sig-name descname"><span class="pre">-t</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-tiffdither-t" title="Permalink to this definition">¶</a></dt>
<dd><p>Set the threshold value for dithering.
By default the threshold value is 128.</p>
</dd></dl>
</section>
<section id="notes">
<h2>Notes<a class="headerlink" href="#notes" title="Permalink to this heading">¶</a></h2>
<p>The dither algorithm is taken from the <strong class="program">tiffmedian</strong>
program (written by Paul Heckbert).</p>
</section>
<section id="see-also">
<h2>See also<a class="headerlink" href="#see-also" title="Permalink to this heading">¶</a></h2>
<p><a class="reference internal" href="pal2rgb.html"><span class="doc">pal2rgb</span></a> (1),
<a class="reference internal" href="fax2tiff.html"><span class="doc">fax2tiff</span></a> (1),
<a class="reference internal" href="tiffinfo.html"><span class="doc">tiffinfo</span></a> (1),
<a class="reference internal" href="tiffcp.html"><span class="doc">tiffcp</span></a> (1),
<a class="reference internal" href="tiff2bw.html"><span class="doc">tiff2bw</span></a> (3tiff)</p>
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<h3><a href="../index.html">Table of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">tiffdither</a><ul>
<li><a class="reference internal" href="#synopsis">Synopsis</a></li>
<li><a class="reference internal" href="#description">Description</a></li>
<li><a class="reference internal" href="#options">Options</a></li>
<li><a class="reference internal" href="#notes">Notes</a></li>
<li><a class="reference internal" href="#see-also">See also</a></li>
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