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<refentry id="tiffdither-1">

<refmeta><refentrytitle>tiffdither</refentrytitle><manvolnum>1</manvolnum>

<refmiscinfo class="date">26 Mar 2004</refmiscinfo>

<refmiscinfo class="sectdesc">&man1;</refmiscinfo>

<refmiscinfo class="software">&release;</refmiscinfo>

<refmiscinfo class="arch">generic</refmiscinfo>

<refmiscinfo class="copyright">&suncopy;</refmiscinfo>

</refmeta>

<indexterm><primary>tiffdither</primary></indexterm><indexterm><primary>convert

a grayscale image to bilevel using dithering</primary></indexterm>

<refnamediv id="tiffdither-1-name"><refname>tiffdither</refname><refpurpose>

convert a grayscale image to bilevel using dithering</refpurpose></refnamediv>

<refsynopsisdiv id="tiffdither-1-synp"><title>&synp-tt;</title>

<cmdsynopsis><command>&cmd;</command><arg choice="opt"><option role="nodash"><replaceable>

options</replaceable></option></arg><arg choice="plain" rep="norepeat"><option

role="nodash"><replaceable>input.tif</replaceable></option></arg><arg choice="plain"

rep="norepeat"><option role="nodash"><replaceable>output.tif</replaceable></option></arg>

</cmdsynopsis></refsynopsisdiv>

<refsect1 id="tiffdither-1-desc"><title>&desc-tt;</title>

<para><command>&cmd;</command> converts a single-channel 8-bit grayscale image

to a bilevel image using Floyd-Steinberg error propagation with thresholding.

</para>

</refsect1>

<refsect1 id="tiffdither-1-opts"><title>&opts-tt;</title>

<para>The following options are supported:</para>

<variablelist termlength="narrow">

<varlistentry><term><option>c</option></term><listitem><para>Specify a compression

scheme to use when writing image data:</para>

<variablelist>

<varlistentry><term><option>c g3</option></term><listitem><para>CCITT Group

3 compression algorithm.</para>

</listitem></varlistentry>

<varlistentry><term><option>c g4</option></term><listitem><para>CCITT Group

4 compression algorithm.</para>

</listitem></varlistentry>

<varlistentry><term><option>c lzw</option></term><listitem><para>Lempel-Ziv

and Welch algorithm.</para>

</listitem></varlistentry>

<varlistentry><term><option>c none</option></term><listitem><para>No compression.

</para>

</listitem></varlistentry>

<varlistentry><term><option>c packbits</option></term><listitem><para>PackBits

compression algorithm.</para>

</listitem></varlistentry>

<varlistentry><term><option>c zip</option></term><listitem><para>Deflate compression

algorithm.</para>

</listitem></varlistentry>

</variablelist><para>By default, <command>&cmd;</command> compresses data

according to the value of the Compression tag found in the source file.</para>

</listitem></varlistentry>

<varlistentry><term><option>f</option></term><listitem><para>Specify the bit

fill order to use to write output data. By default, <command>&cmd;</command>

creates a new file with the same fill order as the original. Specify <option>

f lsb2msb</option> to force data to be written with the FillOrder tag set

to LSB2MSB. Specify <option>f msb2lsb</option> to force data to be written

with the FillOrder tag set to MSB2LSB.</para>

</listitem></varlistentry>

<varlistentry><term><option>t</option></term><listitem><para>Set the threshold

value for dithering. By default, the threshold value is 128.</para>

</listitem></varlistentry>

</variablelist></refsect1>

<refsect1 id="tiffdither-1-oper"><title>&oper-tt;</title>

<para>The following operands are supported:</para>

<variablelist termlength="narrow">

<varlistentry><term><option role="nodash"><replaceable>input.tif</replaceable></option></term>

<listitem><para>The name of the input file.</para>

</listitem></varlistentry>

<varlistentry><term><option role="nodash"><replaceable>output.tif</replaceable></option></term>

<listitem><para>The name of the output file.</para>

</listitem></varlistentry>

</variablelist></refsect1>

<refsect1 id="tiffdither-1-exde"><title>&exde-tt;</title>

<para>The CCITT Group 3 and Group 4 compression algorithms can only be used

with bilevel data.</para>

<para>Group 3 compression can be specified together with several T.4-specific

options:</para>

<variablelist>

<varlistentry><term><option role="nodash">1d</option></term><listitem><para>

1-dimensional encoding</para>

</listitem></varlistentry>

<varlistentry><term><option role="nodash">2d</option></term><listitem><para>

2-dimensional encoding</para>

</listitem></varlistentry>

<varlistentry><term><option role="nodash">fill</option></term><listitem><para>

Force each encoded scanline to be zero-filled so that the terminating EOL

code lies on a byte boundary.</para>

</listitem></varlistentry>

</variablelist><para>Group 3-specific options are specified by appending a

colon-separated list to the <option role="nodash">g3</option> option. For

example, specify <option>c</option> <option role="nodash">g3:2d:fill</option>

to get 2D-encoded data with byte-aligned EOL codes.</para>

<para>LZW compression can be specified together with a predictor value. A

predictor value of 2 causes each scanline of the output image to undergo horizontal

differencing before being encoded. A predictor value of 1 forces each scanline

to be encoded without differencing.</para>

<para>LZW-specific options are specified by appending a colon-separated list

to the <option role="nodash">lzw</option> option. For example, specify <option>

c</option> <option role="nodash">lzw:2</option> for LZW compression with horizontal

differencing.</para>

</refsect1>

<refsect1 id="tiffdither-1-attr"><title>&attr-tt;</title>

<para>See <olink targetdocent="REFMAN5" localinfo="attributes-5"><citerefentry>

<refentrytitle>attributes</refentrytitle><manvolnum>5</manvolnum></citerefentry></olink>

for descriptions of the following attributes:</para>

<informaltable frame="all">

<tgroup cols="2" colsep="1" rowsep="1"><colspec colname="COLSPEC0" colwidth="1*">

<colspec colname="COLSPEC1" colwidth="1*">

<thead>

<row><entry align="center" valign="middle">ATTRIBUTE TYPE</entry><entry align="center"

valign="middle">ATTRIBUTE VALUE</entry></row>

</thead>

<tbody>

<row><entry><para>Availability</para></entry><entry><para>image/library/libtiff</para></entry>

</row>

<row><entry colname="COLSPEC0"><para>Interface stability</para></entry><entry

colname="COLSPEC1"><para>Uncommitted</para></entry></row>

</tbody>

</tgroup>

</informaltable>

</refsect1>

<refsect1 id="tiffdither-1-also"><title>&also-tt;</title>

<para>

<citerefentry><refentrytitle>pal2rgb</refentrytitle><manvolnum>1</manvolnum></citerefentry>,

<citerefentry><refentrytitle>fax2tiff</refentrytitle><manvolnum>1</manvolnum></citerefentry>,

<citerefentry><refentrytitle>tiffinfo</refentrytitle><manvolnum>1</manvolnum></citerefentry>,

<citerefentry><refentrytitle>tiffcp</refentrytitle><manvolnum>1</manvolnum></citerefentry>,

<citerefentry><refentrytitle>tiff2bw</refentrytitle><manvolnum>1</manvolnum></citerefentry>,

<citerefentry><refentrytitle>libtiff</refentrytitle><manvolnum>3</manvolnum></citerefentry>

</para>

</refsect1>

<refsect1 id="tiffdither-1-note"><title>&note-tt;</title>

<para>Updated by Breda McColgan, Sun Microsystems Inc., 2004.</para>

</refsect1>

</refentry>