Man Pages

tiffdither(1) - phpMan tiffdither(1) - phpMan

Command: man perldoc info search(apropos)  


TIFFDITHER(1)                                                    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 prop-
       agation with thresholding.

OPTIONS
       -c     Specify the compression to use for data written to the output file: none for  no  compression,  packbits
              for  PackBits  compression,  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
              appending 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 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 append-
              ing 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 .

       -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.remotesensing.org/libtiff/



libtiff                       September 20, 2005                 TIFFDITHER(1)