NAME

       ppmcolormask - produce mask of areas of a certain color in a PPM file

SYNOPSIS

       ppmcolormask color [ppmfile]

DESCRIPTION

       Reads  a  PPM  file as input.  Produces a PBM (bitmap) file as output.  The output file is
       the same dimensions as the input file and is black in all places where the input  file  is
       the color color, and white everywhere else.

       The output of ppmcolormask is useful as an alpha mask input to pnmcomp.  Note that you can
       generate such an alpha mask automatically as you convert to PNG format  with  pnmtopng(1).
       Use its -transparent option.

       ppmfile  is  the  input  file.   If  you don't specify ppmfile, the input is from Standard
       Input.

       The output goes to Standard Output.

       You can specify color five ways:

       o      An X11-style color name (e.g.  black).

       o      An X11-style hexadecimal specifier: rgb:r/g/b, where r g  and  b  are  each  1-  to
              4-digit hexadecimal numbers.

       o      An  X11-style  decimal  specifier:  rgbi:r/g/b,  where r g and b are floating point
              numbers between 0 and 1.

       o      For backwards compatibility, an old-X11-style hexadecimal  number:  #rgb,  #rrggbb,
              #rrrgggbbb, or #rrrrggggbbbb.

       o      For backwards compatibility, a triplet of numbers separated by commas: r,g,b, where
              r g and b are floating point numbers between 0 and 1.  (This style was added before
              MIT came up with the similar rgbi style.)

SEE ALSO

       pgmtoppm(1), pnmcomp(1), pbmmask(1), ppm(5)

AUTHOR

       Bryan Henderson (bryanh@giraffe-data.com)

                                          14 April 2000                           ppmcolormask(1)