Ppmcolormask User Manual(0) Ppmcolormask User Manual(0)
ppmcolormask - produce mask of areas of a certain color in a PPM file
ppmcolormask -color=color_list [ppmfile]
ppmcolormask color [ppmfile]
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
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 an alpha mask input to pamcomp. Note that you can
generate such an alpha mask automatically as you convert to PNG format with pnmtopng(1)
ppmfile is the input file. If you don't specify ppmfile, the input is from Standard
The output goes to Standard Output.
In the obsolete alternative syntax, specifying the color names a single exact color to be
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 specify-
ing colors in the input image.
To make a mask of an image's background, without having to tell it what color it is, use
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).
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 ppm_parsecolor() library routine
<libppm.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 func-
tions defined in the HSV color space. Although more complex algorithms for fuzzy
color matching exist, this algorithm is intentionally simplified to achieve a sat-
isfactory 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.
pambackground(1) , ppmchange(1) , pgmtoppm(1) , pamcomp(1) , pbmmask(1) , ppm(1)
netpbm documentation 1 May 2006 Ppmcolormask User Manual(0)