1Ppmcolormask User Manual(0)                        Ppmcolormask User Manual(0)
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NAME

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

10       ppmcolormask -color=color_list [ppmfile]
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12       ppmcolormask color [ppmfile]
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EXAMPLES

16       <code>
17           ppmcolormask -color red testimg.ppm >redmask.pbm
18           pamcomp background.ppm testimg.ppm -alpha=redmask.pbm >test.ppm
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20           ppmcolormask -color=red,pink,salmon testimg.ppm >reddishmask.pbm
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22           ppmcolormask -color=bk:red,bk:orange,bk:yellow testimg.ppm >firemask.pbm
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24       </code>
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DESCRIPTION

28       This program is part of Netpbm(1).
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30       ppmcolormask reads a PPM file as input and produces a PBM (bitmap) file
31       as output.  The output file is the same dimensions as  the  input  file
32       and is black in all places where the input file is a color indicated by
33       the -color option, and white everywhere else.
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35       The output of ppmcolormask is useful as an alpha mask input to pamcomp.
36       Note that you can generate such an alpha mask automatically as you con‐
37       vert to PNG format with pnmtopng(1).Useits-transparent option.
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39       ppmfile is the input file.  If you don't specify ppmfile, the input  is
40       from Standard Input.
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42       The output goes to Standard Output.
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44       In the obsolete alternative syntax, specifying the color names a single
45       exact color to be masked.
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47       ppmchange does a similar thing: it modifies an image by changing colors
48       you  specify  to  other  colors you specify.  The two programs give you
49       somewhat different means of specifying colors in the input image.
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51       To make a mask of an image's background, without having to tell it what
52       color it is, use pambackground.
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OPTIONS

56       -color=color_list
57              This mandatory option specifies the colors that are to be masked
58              (where the image is one of these colors, the output mask will be
59              black).
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61              Examples:
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65       ·      -color=red
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67       ·      -color=red,pink,salmon
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69       ·      -color=rgb:80/80/ff
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71       ·      -color=bk:red,bk:orange,bk:yellow
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74              color_list  is a list of colors separated by commas.  Each color
75              is either an exact color name as described for the  argument  of
76              the ppm_parsecolor() library routine ⟨libppm.html#colorname⟩  or
77              one of the Berlin-Kay color names ⟨libppm.html#berlinkay⟩ .   In
78              the  latter  case,  all colors that are better described by that
79              Berlin-Kay color name than any other are in the mask set.
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81              The algorithm ppmcolormask uses to determine to which  colors  a
82              Berlin-Kay  color  name  applies is based on a Sugeno-type fuzzy
83              inference system developed by  Kenan  Kalajdzic  in  2006.   The
84              fuzzy  model  consists  of partially linear membership functions
85              defined in the HSV color space.   Although  more  complex  algo‐
86              rithms  for fuzzy color matching exist, this algorithm is inten‐
87              tionally simplified to achieve a satisfactory speed using  rela‐
88              tively compact code.
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90              This  option  was new in Netpbm 10.34 (June 2006).  Before that,
91              you must use the color argument and cannot specify a  Berlin-Kay
92              color.
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SEE ALSO

98       pambackground(1),  ppmchange(1),  pgmtoppm(1),  pamcomp(1), pbmmask(1),
99       ppm(1)
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103netpbm documentation              1 May 2006       Ppmcolormask User Manual(0)