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TIFFDITHER(1)		    General Commands Manual		 TIFFDITHER(1)

NAME
       tiffdither - convert a greyscale	image to bilevel using dithering

SYNOPSIS
       tiffdither [ options ] input.tif	output.tif

DESCRIPTION
       tiffdither converts a single channel 8-bit greyscale image to a bilevel
       image using Floyd-Steinberg error propagation with thresholding.

OPTIONS
       -c     Specify the compression to use for data written  to  the	output
	      file:  none  for	no compression,	packbits for PackBits compres-
	      sion, lzw	for Lempel-Ziv & Welch compression,  zip  for  Deflate
	      compression,  g3 for CCITT Group 3 (T.4) compression, and	g4 for
	      CCITT Group 4 (T.6) compression.	 By  default  tiffdither  will
	      compress	data  according	 to  the  value	of the Compression tag
	      found in the source file.

	      The CCITT	Group 3	and Group 4 compression	algorithms can only be
	      used with	bilevel	data.

	      Group  3	compression  can  be  specified	 together with several
	      T.4-specific options: 1d	for  1-dimensional  encoding,  2d  for
	      2-dimensional  encoding, and fill	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 ap-
	      pending a	``:''-separated	list to	the ``g3''  option;  e.g.   -c
	      g3:2d:fill to get	2D-encoded data	with byte-aligned EOL codes.

	      LZW  compression	can  be	 specified  together  with a predictor
	      value.  A	predictor value	of 2 causes each scanline of the  out-
	      put  image  to  undergo horizontal differencing before it	is en-
	      coded; 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.	-c  lzw:2  for
	      LZW compression with horizontal differencing.

       -f     Specify  the  bit	 fill order to use in writing output data.  By
	      default, tiffdither will create a	new file with  the  same  fill
	      order as the original.  Specifying -f lsb2msb will force data to
	      be written with the FillOrder tag	set  to	 LSB2MSB  ,  while  -f
	      msb2lsb will force data to be written with the FillOrder tag set
	      to MSB2LSB .

       -r     Make each	strip have no more than	the given number of rows.

       -t     Set the threshold	value for dithering.  By default the threshold
	      value is 128.

NOTES
       The  dither  algorithm is taken from the	tiffmedian(1) program (written
       by Paul Heckbert).

SEE ALSO
       pal2rgb(1),   fax2tiff(1),    tiffinfo(1),    tiffcp(1),	   tiff2bw(1),
       libtiff(3TIFF)

       Libtiff library home page: http://www.simplesystems.org/libtiff/

libtiff			      September	20, 2005		 TIFFDITHER(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | NOTES | SEE ALSO

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