tiffmedian(1)

TIFFMEDIAN(1)            USER COMMANDS              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  pred-
          ictor  value.  A predictor value of 2 causes each scan-
          line of the output image  to  undergo  horizontal  dif-
          ferencing  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, tiff-
          median 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(3)

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

                  Last change: October 15, 1995                 1