PPMTOSIXEL

NAME

      ppmtosixel - convert a portable pixmap into DEC sixel format

SYNOPSIS

      ppmtosixel [-raw] [-margin] [ppmfile]

DESCRIPTION

      Reads a portable pixmap as input.  Produces sixel commands (SIX) as
      output.  The output is formatted for color printing, e.g. for a DEC
      LJ250 color inkjet printer.
      If RGB values from the PPM file do not have maxval=100, the RGB values
      are rescaled.  A printer control header and a color assignment table
      begin the SIX file.  Image data is written in a compressed format by
      default.  A printer control footer ends the image file.

OPTIONS

      -raw If specified, each pixel will be explicitly described in the
           image file.  If -raw is not specified, output will default to
           compressed format in which identical adjacent pixels are replaced
           by "repeat pixel" commands.  A raw file is often an order of
           magnitude larger than a compressed file and prints much slower.
      -margin
           If -margin is not specified, the image will be start at the left
           margin (of the window, paper, or whatever).  If -margin is
           specified, a 1.5 inch left margin will offset the image.

PRINTING

      Generally, sixel files must reach the printer unfiltered.  Use the lpr
      -x option or cat filename > /dev/tty0?.

BUGS

      Upon rescaling, truncation of the least significant bits of RGB values
      may result in poor color conversion.  If the original PPM maxval was
      greater than 100, rescaling also reduces the image depth.  While the
      actual RGB values from the ppm file are more or less retained, the
      color palette of the LJ250 may not match the colors on your screen.
      This seems to be a printer limitation.

SEE ALSO

      ppm(5)

AUTHOR

      Copyright (C) 1991 by Rick Vinci.