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tiffmedian(1)


NAME

   tiffmedian - apply the median cut algorithm to data in a TIFF file

SYNOPSIS

   tiffmedian [ options ] input.tif output.tif

DESCRIPTION

   tiffmedian  applies  the  median  cut  algorithm  to  an  RGB  image in
   input.tif to generate a palette image that is  written  to  output.tif.
   The generated colormap has, by default, 256 entries.  The image data is
   quantized by mapping each pixel to the  closest  color  values  in  the
   colormap.

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, and zip for
          Deflate compression.  By default tiffmedian will  compress  data
          according  to  the  value  of  the  Compression tag found in the
          source file.

          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 appending a
          ``:''-separated  list  to the ``lzw'' option; e.g.  -c lzw:2 for
          LZW compression with horizontal differencing.

   -C     Specify the number of entries to use in the generated  colormap.
          By default all 256 entries/colors are used.

   -f     Apply  Floyd-Steinberg  dithering  before  selecting  a colormap
          entry.

   -r     Specify the number of rows (scanlines) in  each  strip  of  data
          written  to the output file.  By default, tiffmedian attempts to
          set the rows/strip that no more than 8 kilobytes of data  appear
          in a strip.

NOTES

   This program is derived from Paul Heckbert's median program.

SEE ALSO

   pal2rgb(1), tiffinfo(1), tiffcp(1), tiffcmp(1), libtiff(3TIFF)

   Color  Image  Quantization  for  Frame  Buffer  Display, Paul Heckbert,
   SIGGRAPH proceedings, 1982, pp. 297-307.

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



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