Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
Pbmmask	User Manual(0)					Pbmmask	User Manual(0)

NAME
       pbmmask - create	a mask bitmap from a regular bitmap

SYNOPSIS
       pbmmask [-expand] [pbmfile]

DESCRIPTION
       This program is part of Netpbm(1).

       pbmmask	reads  a PBM image as input and	Generates a corresponding mask
       of the foreground areas as another PBM image.

       The color to be interpreted as  "background"  is	 determined  automati-
       cally.  Regardless of which color is background,	the mask will be white
       where the background is and black where the figure is.

       This lets you do	a masked paste like this, for  objects	with  a	 black
       background:

	   pbmmask obj > objmask
	   pnmpaste < dest -and	objmask	<x> <y>	| pnmpaste -or obj <x> <y>

       For  objects with a white background, you can either invert them	or add
       a step:
	   pbmmask obj > objmask
	   pnminvert objmask | pnmpaste	-and obj 0 0 > blackback
	   pnmpaste < dest -and	objmask	<x> <y>	| pnmpaste -or blackback <x> <y>

       Note that this three-step version works for objects  with  black	 back-
       grounds too, if you don't care about the	wasted time.

       You  can	 also use masks	with grayscale and color images, using the pn-
       marith tool.  For instance:

	   ppmtopgm obj.ppm | pamditherbw -threshold | pbmmask > objmask.pbm
	   pnmarith -multiply dest.ppm objmask.pbm > t1.ppm
	   pnminvert objmask.pbm | pnmarith -multiply obj.ppm -	> t2.ppm
	   pnmarith -add t1.ppm	t2.ppm

       An interesting variation	on this	is to pipe the mask through  pnmsmooth
       before  using  it.  This	makes the boundary between the two images less
       sharp.

OPTIONS
       -expand
	      Expands the mask by one pixel out	from the image.	 This is  use-
	      ful  if  you  want  a little white border	around your image.  (A
	      better solution might be to turn the pbmlife program into	a gen-
	      eral cellular automaton tool...)

SEE ALSO
       ppmcolormask(1),	 pnmpaste(1),  pnminvert(1), pnmarith(1), pnmsmooth(1)
       pbm(5),

AUTHOR
       Copyright (C) 1988 by Jef Poskanzer.

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/pbmmask.html

netpbm documentation		08 August 1989		Pbmmask	User Manual(0)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | SEE ALSO | AUTHOR | DOCUMENT SOURCE

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=pbmmask&sektion=1&manpath=FreeBSD+13.0-RELEASE+and+Ports>

home | help