NAME

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

SYNOPSIS

       ppmcolormask -color=color_list [ppmfile]

       ppmcolormask color [ppmfile]

EXAMPLES

           ppmcolormask -color red testimg.ppm >redmask.pbm
           pamcomp background.ppm testimg.ppm -alpha=redmask.pbm >test.ppm

           ppmcolormask -color=red,pink,salmon testimg.ppm >reddishmask.pbm

           ppmcolormask -color=bk:red,bk:orange,bk:yellow testimg.ppm >firemask.pbm

DESCRIPTION

       This program is part of Netpbm(1).

       ppmcolormask  reads  a  PPM file as input and 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 a color indicated by the -color option, and white everywhere else.

       The  output  of ppmcolormask is useful as a transparency mask input to pamcomp.  Note that
       you don't need ppmcolormask and pamcomp if you  are  ultimately  converting  to  PNG  with
       pnmtopng because the -transparent option on pnmtopng does the same thing.

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

       The output goes to Standard Output.

       In the obsolete alternative syntax, specifying the color names a single exact color to  be
       masked.

       ppmchange  does  a  similar  thing: it modifies an image by changing colors you specify to
       other colors you  specify.   The  two  programs  give  you  somewhat  different  means  of
       specifying colors in the input image.

       To  make  a mask of an image's background, without having to tell it what color it is, use
       pambackground.

OPTIONS

       In addition to the options common to all programs based on libnetpbm (most notably -quiet,
       see
        Common  Options  ⟨index.html#commonoptions⟩  ),  ppmcolormask  recognizes  the  following
       command line option:

       -color=color_list
              This mandatory option specifies the colors that are to be masked (where  the  image
              is one of these colors, the output mask will be black).

              Examples:

       •      -color=red

       •      -color=red,pink,salmon

       •      -color=rgb:80/80/ff

       •      -color=bk:red,bk:orange,bk:yellow

              color_list  is a list of colors separated by commas.  Each color is either an exact
              color name as described for the argument of the  pnm_parsecolor()  library  routine
              ⟨libnetpbm_image.html#colorname⟩      or   one   of   the  Berlin-Kay  color  names
              ⟨libppm.html#berlinkay⟩ .  In the latter case, all colors that are better described
              by that Berlin-Kay color name than any other are in the mask set.

              The  algorithm  ppmcolormask  uses  to determine to which colors a Berlin-Kay color
              name applies is based on a Sugeno-type fuzzy inference system  developed  by  Kenan
              Kalajdzic  in  2006.   The  fuzzy  model  consists  of  partially linear membership
              functions defined in the HSV color space.  Although  more  complex  algorithms  for
              fuzzy color matching exist, this algorithm is intentionally simplified to achieve a
              satisfactory speed using relatively compact code.

              This option was new in Netpbm 10.34 (June 2006).  Before that,  you  must  use  the
              color argument and cannot specify a Berlin-Kay color.

SEE ALSO

       pamfind(1),   pambackground(1),   ppmchange(1),   pgmtoppm(1),   pamcomp(1),   pbmmask(1),
       pnmtopng(1), ppm(1)

DOCUMENT SOURCE

       This manual page was generated by the Netpbm tool 'makeman' from HTML source.  The  master
       documentation is at

              http://netpbm.sourceforge.net/doc/ppmcolormask.html