1<html> 2<head> 3<meta name="generator" content="groff -Thtml, see www.gnu.org"> 4<meta name="Content-Style" content="text/css"> 5<title>TIFFDITHER</title> 6</head> 7<body> 8 9<h1 align=center>TIFFDITHER</h1> 10<a href="#NAME">NAME</a><br> 11<a href="#SYNOPSIS">SYNOPSIS</a><br> 12<a href="#DESCRIPTION">DESCRIPTION</a><br> 13<a href="#OPTIONS">OPTIONS</a><br> 14<a href="#NOTES">NOTES</a><br> 15<a href="#SEE ALSO">SEE ALSO</a><br> 16 17<hr> 18<!-- Creator : groff version 1.17.2 --> 19<!-- CreationDate: Mon Dec 22 00:39:34 2003 --> 20<a name="NAME"></a> 21<h2>NAME</h2> 22<table width="100%" border=0 rules="none" frame="void" 23 cols="2" cellspacing="0" cellpadding="0"> 24<tr valign="top" align="left"> 25<td width="10%"></td><td width="90%"> 26tiffdither - convert a greyscale image to bilevel using dithering</td></table> 27<a name="SYNOPSIS"></a> 28<h2>SYNOPSIS</h2> 29 30<table width="100%" border=0 rules="none" frame="void" 31 cols="2" cellspacing="0" cellpadding="0"> 32<tr valign="top" align="left"> 33<td width="10%"></td><td width="90%"> 34<b>tiffdither</b> [ <i>options</i> ] <i>input.tif 35output.tif</i></td></table> 36<a name="DESCRIPTION"></a> 37<h2>DESCRIPTION</h2> 38 39<table width="100%" border=0 rules="none" frame="void" 40 cols="2" cellspacing="0" cellpadding="0"> 41<tr valign="top" align="left"> 42<td width="10%"></td><td width="90%"> 43<i>tiffdither</i> converts a single channel 8-bit greyscale 44image to a bilevel image using Floyd-Steinberg error 45propagation with threholding.</td></table> 46<a name="OPTIONS"></a> 47<h2>OPTIONS</h2> 48 49<table width="100%" border=0 rules="none" frame="void" 50 cols="2" cellspacing="0" cellpadding="0"> 51<tr valign="top" align="left"> 52<td width="10%"></td><td width="90%"> 53<b>-c</b></td></table> 54 55<table width="100%" border=0 rules="none" frame="void" 56 cols="2" cellspacing="0" cellpadding="0"> 57<tr valign="top" align="left"> 58<td width="21%"></td><td width="79%"> 59Specify the compression to use for data written to the 60output file: <b>none</b> for no compression, <b>packbits</b> 61for PackBits compression, <b>lzw</b> for Lempel-Ziv & 62Welch compression, <b>zip</b> for Deflate compression, 63<b>g3</b> for CCITT Group 3 (T.4) compression, and <b>g4</b> 64for CCITT Group 4 (T.6) compression. By default 65<i>tiffdither</i> will compress data according to the value 66of the <i>Compression</i> tag found in the source 67file.</td></table> 68 69<table width="100%" border=0 rules="none" frame="void" 70 cols="2" cellspacing="0" cellpadding="0"> 71<tr valign="top" align="left"> 72<td width="21%"></td><td width="79%"> 73The <small>CCITT</small> Group 3 and Group 4 compression 74algorithms can only be used with bilevel data.</td></table> 75 76<table width="100%" border=0 rules="none" frame="void" 77 cols="2" cellspacing="0" cellpadding="0"> 78<tr valign="top" align="left"> 79<td width="21%"></td><td width="79%"> 80Group 3 compression can be specified together with several 81T.4-specific options: <b>1d</b> for 1-dimensional encoding, 82<b>2d</b> for 2-dimensional encoding, and <b>fill</b> to 83force each encoded scanline to be zero-filled so that the 84terminating EOL code lies on a byte boundary. Group 853-specific options are specified by appending a 86``:''-separated list to the ``g3'' option; e.g. <b>-c 87g3:2d:fill</b> to get 2D-encoded data with byte-aligned EOL 88codes.</td></table> 89 90<table width="100%" border=0 rules="none" frame="void" 91 cols="2" cellspacing="0" cellpadding="0"> 92<tr valign="top" align="left"> 93<td width="21%"></td><td width="79%"> 94<small>LZW</small> compression can be specified together 95with a <i>predictor</i> value. A predictor value of 2 causes 96each scanline of the output image to undergo horizontal 97differencing before it is encoded; a value of 1 forces each 98scanline to be encoded without differencing. LZW-specific 99options are specified by appending a ``:''-separated list to 100the ``lzw'' option; e.g. <b>-c lzw:2</b> for 101<small>LZW</small> compression with horizontal 102differencing.</td></table> 103 104<table width="100%" border=0 rules="none" frame="void" 105 cols="2" cellspacing="0" cellpadding="0"> 106<tr valign="top" align="left"> 107<td width="10%"></td><td width="90%"> 108<b>-f</b></td></table> 109 110<table width="100%" border=0 rules="none" frame="void" 111 cols="2" cellspacing="0" cellpadding="0"> 112<tr valign="top" align="left"> 113<td width="21%"></td><td width="79%"> 114Specify the bit fill order to use in writing output data. By 115default, <i>tiffdither</i> will create a new file with the 116same fill order as the original. Specifying <b>-f 117lsb2msb</b> will force data to be written with the FillOrder 118tag set to <small>LSB2MSB ,</small> while <b>-f msb2lsb</b> 119will force data to be written with the FillOrder tag set to 120<small>MSB2LSB .</small></td></table> 121 122<table width="100%" border=0 rules="none" frame="void" 123 cols="2" cellspacing="0" cellpadding="0"> 124<tr valign="top" align="left"> 125<td width="10%"></td><td width="90%"> 126<b>-t</b></td></table> 127 128<table width="100%" border=0 rules="none" frame="void" 129 cols="2" cellspacing="0" cellpadding="0"> 130<tr valign="top" align="left"> 131<td width="21%"></td><td width="79%"> 132Set the threshold value for dithering. By default the 133threshold value is 128.</td></table> 134<a name="NOTES"></a> 135<h2>NOTES</h2> 136 137<table width="100%" border=0 rules="none" frame="void" 138 cols="2" cellspacing="0" cellpadding="0"> 139<tr valign="top" align="left"> 140<td width="10%"></td><td width="90%"> 141The dither algorithm is taken from the <i>tiffmedian</i>(1) 142program (written by Paul Heckbert).</td></table> 143<a name="SEE ALSO"></a> 144<h2>SEE ALSO</h2> 145 146<table width="100%" border=0 rules="none" frame="void" 147 cols="2" cellspacing="0" cellpadding="0"> 148<tr valign="top" align="left"> 149<td width="10%"></td><td width="90%"> 150<i>pal2rgb</i>(1), <i>fax2tiff</i>(1), <i>tiffinfo</i>(1), 151<i>tiffcp</i>(1), <i>tiff2bw</i>(1), 152<i>libtiff</i>(3)</td></table> 153<hr> 154</body> 155</html> 156