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<title>TIFFDITHER</title>
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<h1 align="center">TIFFDITHER</h1>
<a href="#NAME">NAME</a><br>
<a href="#SYNOPSIS">SYNOPSIS</a><br>
<a href="#DESCRIPTION">DESCRIPTION</a><br>
<a href="#OPTIONS">OPTIONS</a><br>
<a href="#NOTES">NOTES</a><br>
<a href="#SEE ALSO">SEE ALSO</a><br>
<hr>
<h2>NAME
<a name="NAME"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">tiffdither
− convert a greyscale image to bilevel using
dithering</p>
<h2>SYNOPSIS
<a name="SYNOPSIS"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>tiffdither</b>
[ <i>options</i> ] <i>input.tif output.tif</i></p>
<h2>DESCRIPTION
<a name="DESCRIPTION"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><i>tiffdither</i>
converts a single channel 8-bit greyscale image to a bilevel
image using Floyd-Steinberg error propagation with
thresholding.</p>
<h2>OPTIONS
<a name="OPTIONS"></a>
</h2>
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<p style="margin-top: 1em"><b>−c</b></p></td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em">Specify the compression to use
for data written to the output file: <b>none</b> for no
compression, <b>packbits</b> for PackBits compression,
<b>lzw</b> for Lempel-Ziv & Welch compression,
<b>zip</b> for Deflate compression, <b>g3</b> for CCITT
Group 3 (T.4) compression, and <b>g4</b> for CCITT Group 4
(T.6) compression. By default <i>tiffdither</i> will
compress data according to the value of the
<i>Compression</i> tag found in the source file.</p></td></tr>
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<p style="margin-left:22%; margin-top: 1em">The
<small>CCITT</small> Group 3 and Group 4 compression
algorithms can only be used with bilevel data.</p>
<p style="margin-left:22%; margin-top: 1em">Group 3
compression can be specified together with several
T.4-specific options: <b>1d</b> for 1-dimensional encoding,
<b>2d</b> for 2-dimensional encoding, and <b>fill</b> 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
‘‘:’’-separated list to the
‘‘g3’’ option; e.g. <b>−c
g3:2d:fill</b> to get 2D-encoded data with byte-aligned EOL
codes.</p>
<p style="margin-left:22%; margin-top: 1em"><small>LZW</small>
compression can be specified together with a
<i>predictor</i> 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
‘‘:’’-separated list to the
‘‘lzw’’ option; e.g. <b>−c
lzw:2</b> for <small>LZW</small> compression with horizontal
differencing.</p>
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<td width="3%">
<p style="margin-top: 1em"><b>−f</b></p></td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em">Specify the bit fill order to
use in writing output data. By default, <i>tiffdither</i>
will create a new file with the same fill order as the
original. Specifying <b>−f lsb2msb</b> will force data
to be written with the <i>FillOrder</i> tag set to
<small>LSB2MSB ,</small> while <b>−f msb2lsb</b> will
force data to be written with the <i>FillOrder</i> tag set
to <small>MSB2LSB .</small></p></td></tr>
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<td width="11%"></td>
<td width="3%">
<p><b>−r</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Make each strip have no more than the given number of
rows.</p> </td></tr>
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<td width="11%"></td>
<td width="3%">
<p><b>−t</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Set the threshold value for dithering. By default the
threshold value is 128.</p></td></tr>
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<h2>NOTES
<a name="NOTES"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">The dither
algorithm is taken from the <b>tiffmedian</b>(1) program
(written by Paul Heckbert).</p>
<h2>SEE ALSO
<a name="SEE ALSO"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>pal2rgb</b>(1),
<b>fax2tiff</b>(1), <b>tiffinfo</b>(1), <b>tiffcp</b>(1),
<b>tiff2bw</b>(1), <b>libtiff</b>(3TIFF)</p>
<p style="margin-left:11%; margin-top: 1em">Libtiff library
home page: <b>http://www.simplesystems.org/libtiff/</b></p>
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