src/tiff/html/man/tiffdither.1.html

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   7 <title>TIFFDITHER</title>
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  10
  11 <h1 align=center>TIFFDITHER</h1>
  12 <a href="#NAME">NAME</a><br>
  13 <a href="#SYNOPSIS">SYNOPSIS</a><br>
  14 <a href="#DESCRIPTION">DESCRIPTION</a><br>
  15 <a href="#OPTIONS">OPTIONS</a><br>
  16 <a href="#NOTES">NOTES</a><br>
  17 <a href="#SEE ALSO">SEE ALSO</a><br>
  18
  19 <hr>
  20 <a name="NAME"></a>
  21 <h2>NAME</h2>
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  28 <p>tiffdither &minus; convert a greyscale image to bilevel
  29 using dithering</p>
  30 </td>
  31 </table>
  32 <a name="SYNOPSIS"></a>
  33 <h2>SYNOPSIS</h2>
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  40 <p><b>tiffdither</b> [ <i>options</i> ] <i>input.tif
  41 output.tif</i></p>
  42 </td>
  43 </table>
  44 <a name="DESCRIPTION"></a>
  45 <h2>DESCRIPTION</h2>
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  52 <p><i>tiffdither</i> converts a single channel 8-bit
  53 greyscale image to a bilevel image using Floyd-Steinberg
  54 error propagation with thresholding.</p>
  55 </td>
  56 </table>
  57 <a name="OPTIONS"></a>
  58 <h2>OPTIONS</h2>
  59 <!-- TABS -->
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  65
  66 <p><b>&minus;c</b></p>
  67 </td>
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  70
  71 <p>Specify the compression to use for data written to the
  72 output file: <b>none</b> for no compression, <b>packbits</b>
  73 for PackBits compression, <b>lzw</b> for Lempel-Ziv &amp;
  74 Welch compression, <b>zip</b> for Deflate compression,
  75 <b>g3</b> for CCITT Group 3 (T.4) compression, and <b>g4</b>
  76 for CCITT Group 4 (T.6) compression. By default
  77 <i>tiffdither</i> will compress data according to the value
  78 of the <i>Compression</i> tag found in the source file.</p>
  79 </td>
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  81 </td>
  82 </table>
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  89 <p>The <small>CCITT</small> Group 3 and Group 4 compression
  90 algorithms can only be used with bilevel data.</p>
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  92 <p>Group 3 compression can be specified together with
  93 several T.4-specific options: <b>1d</b> for 1-dimensional
  94 encoding, <b>2d</b> for 2-dimensional encoding, and
  95 <b>fill</b> to force each encoded scanline to be zero-filled
  96 so that the terminating EOL code lies on a byte boundary.
  97 Group 3-specific options are specified by appending a
  98 &lsquo;&lsquo;:&rsquo;&rsquo;-separated list to the
  99 &lsquo;&lsquo;g3&rsquo;&rsquo; option; e.g. <b>&minus;c
 100 g3:2d:fill</b> to get 2D-encoded data with byte-aligned EOL
 101 codes.</p>
 102 <!-- INDENTATION -->
 103 <p><small>LZW</small> compression can be specified together
 104 with a <i>predictor</i> value. A predictor value of 2 causes
 105 each scanline of the output image to undergo horizontal
 106 differencing before it is encoded; a value of 1 forces each
 107 scanline to be encoded without differencing. LZW-specific
 108 options are specified by appending a
 109 &lsquo;&lsquo;:&rsquo;&rsquo;-separated list to the
 110 &lsquo;&lsquo;lzw&rsquo;&rsquo; option; e.g. <b>&minus;c
 111 lzw:2</b> for <small>LZW</small> compression with horizontal
 112 differencing.</p>
 113 </td>
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 115 <!-- TABS -->
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 121
 122 <p><b>&minus;f</b></p>
 123 </td>
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 126
 127 <p>Specify the bit fill order to use in writing output
 128 data. By default, <i>tiffdither</i> will create a new file
 129 with the same fill order as the original. Specifying
 130 <b>&minus;f lsb2msb</b> will force data to be written with
 131 the FillOrder tag set to <small>LSB2MSB ,</small> while
 132 <b>&minus;f msb2lsb</b> will force data to be written with
 133 the FillOrder tag set to <small>MSB2LSB .</small></p>
 134 </td>
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 136 </td>
 137 <tr valign="top" align="left">
 138 <td width="10%"></td>
 139 <td width="3%">
 140
 141 <p><b>&minus;t</b></p>
 142 </td>
 143 <td width="5%"></td>
 144 <td width="80%">
 145
 146 <p>Set the threshold value for dithering. By default the
 147 threshold value is 128.</p>
 148 </td>
 149 <td width="0%">
 150 </td>
 151 </table>
 152 <a name="NOTES"></a>
 153 <h2>NOTES</h2>
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 160 <p>The dither algorithm is taken from the
 161 <b>tiffmedian</b>(1) program (written by Paul Heckbert).</p>
 162 </td>
 163 </table>
 164 <a name="SEE ALSO"></a>
 165 <h2>SEE ALSO</h2>
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 172 <p><b>pal2rgb</b>(1), <b>fax2tiff</b>(1),
 173 <b>tiffinfo</b>(1), <b>tiffcp</b>(1), <b>tiff2bw</b>(1),
 174 <b>libtiff</b>(3TIFF)</p>
 175 <!-- INDENTATION -->
 176 <p>Libtiff library home page:
 177 <b>http://www.remotesensing.org/libtiff/</b></p>
 178 </td>
 179 </table>
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