NAME
      to8 - Convert a 24 bit RLE file to eight bits
      using dithering.

 SYNOPSIS
      to8 [ -g display_gamma ] [ -{iI} image_gamma ] [ -o outfile ] [ infile
      ]

 DESCRIPTION
      To8 Converts an image with 24 bit pixel
      values (eight bits each of red, green and
      blue) to eight bits of color using a dithered
      color map (the special color map is
      automatically written into the output file).
      If no input file is specified, to8 reads from
      stdin.  If no output file is specified with
      -o it writes the result to the standard
      output.

      Other options allow control over the gamma,
      or contrast, of the image.  The dithering
      process assumes that the incoming image has a
      gamma of 1.0 (i.e., a 200 in the input
      represents an intensity twice that of a 100.)
      If this is not the case, the input values
      must be adjusted before dithering via the -i
      or -I option.  The input file may also
      specify the gamma of the image via a picture
      comment (see below).  The output display is
      assumed to have a gamma of 2.5 (standard for
      color TV monitors).  This may be modified via
      the -g option if a display with a different
      gamma is used.

      To8 will put a picture comment into the
      output file indicating the display gamma
      assumed in constructing the dithering color
      map.

 OPTIONS
      -i image_gamma
           Specify the gamma (contrast) of the
           image.  A low contrast image, suited for
           direct display without compensation on a
           high contrast monitor (as most monitors
           are) will have a gamma of less than one.
           The default image gamma is 1.0.  Image
           gamma may also be specified by a picture
           comment in the RLE (5) file of the form
           image_gamma=gamma.  The command line
           argument will override the value in the
           file if specified.

      -I image_gamma
           An alternate method of specifying the
           image gamma, the number following -I is
           the gamma of the display for which the
           image was originally computed (and is
           therefore 1.0 divided by the actual
           gamma of the image).  Image display
           gamma may also be specified by a picture
           comment in the RLE (5) file of the form
           display_gamma=gamma.  The command line
           argument will override the value in the
           file if specified.

      -g display_gamma
           Specify the gamma of the X display
           monitor.  The default value is 2.5,
           suitable for most color TV monitors
           (this is the gamma value assumed by the
           NTSC video standard).

      -o outfile
           If specified, the output will be written
           to this file.  If outfile is "-", or if
           it is not specified, the output will be
           written to the standard output stream.

 SEE ALSO
      tobw(1), getx11(1), mcut(1), rlequant(1),
      urt(1), dither(3), RLE(5).

 AUTHOR
      Spencer Thomas
















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