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 ), 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  or one of the Berlin-Kay color
              names  .   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

netpbm documentation                               01 May 2006                       Ppmcolormask User Manual(1)