# pbmmask(1) - man - phpman

> **TLDR:** Create a mask bitmap from a regular bitmap.
>
- Create a mask bitmap separating background from foreground:
  `pbmmask {{path/to/image.pbm}} > {{path/to/output.pbm}}`
- Expand the generated mask by one pixel:
  `pbmmask {{-r|-expand}} {{path/to/image.pbm}} > {{path/to/output.pbm}}`

*Source: tldr-pages*

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[pbmmask(1)](https://www.chedong.com/phpMan.php/man/pbmmask/1/markdown)                             General Commands Manual                            [pbmmask(1)](https://www.chedong.com/phpMan.php/man/pbmmask/1/markdown)



## NAME
       pbmmask - create a mask bitmap from a regular bitmap

## SYNOPSIS
       **pbmmask** [**-expand**] [_pbmfile_]

## DESCRIPTION
       Reads a portable bitmap as input.  Creates a corresponding mask bitmap and writes it out.

       The color to be interpreted as "background" is determined automatically.  Regardless of which
       color is background, the mask will be white where the background is and black where the  fig‐
       ure 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 backgrounds too, if you don't
       care about the wasted time.

       You can also use masks with graymaps and pixmaps, using the _pnmarith_ tool.  For instance:
           ppmtopgm obj.ppm | pgmtopbm -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 the _pnmsmooth_ script before  us‐
       ing 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 useful if you want a little
              white border around your image.  (A better solution might be to turn the _pbmlife_  tool
              into a general cellular automaton tool...)



## SEE ALSO
       [**ppmcolormask**(1)](https://www.chedong.com/phpMan.php/man/ppmcolormask/1/markdown), [**pnmpaste**(1)](https://www.chedong.com/phpMan.php/man/pnmpaste/1/markdown), [**pnminvert**(1)](https://www.chedong.com/phpMan.php/man/pnminvert/1/markdown), [**pbm**(5)](https://www.chedong.com/phpMan.php/man/pbm/5/markdown), [**pnmarith**(1)](https://www.chedong.com/phpMan.php/man/pnmarith/1/markdown), [**pnmsmooth**(1)](https://www.chedong.com/phpMan.php/man/pnmsmooth/1/markdown)

## AUTHOR
       Copyright (C) 1988 by Jef Poskanzer.



                                           08 August 1989                                 [pbmmask(1)](https://www.chedong.com/phpMan.php/man/pbmmask/1/markdown)