TIFFMEDIAN(1)                                     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 Lem-
              pel-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 hor-
              izontal 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  com-
              pression with horizontal differencing.

       -C     Specify  the number of entries to use in the gen-
              erated colormap.  By default all 256 entries/col-
              ors 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 pro-
       gram.

SEE ALSO
       pal2rgb(1),    tiffinfo(1),    tiffcp(1),    tiffcmp(1),
       libtiff(3)

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



                        October 15, 1995          TIFFMEDIAN(1)
