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
R color ,
and white everywhere else.
The output of
ppmcolormask
is useful as an alpha mask input to
R 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
R 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.
R 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
AUTHOR
Bryan Henderson (bryanh@giraffe-data.com)
\" Contributed to the public domain.
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