pbmmask

pbmmask

NAME SYNOPSIS DESCRIPTION SEE ALSO AUTHOR

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

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

a black background

pbmmask obj

For objects with a white background, you can either invert them or add a step

pbmmask obj

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

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

-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

pnmpaste(1), pnminvert(1), pbm(5), pnmarith(1), pnmsmooth(1)

AUTHOR

Copyright (C) 1988 by Jef Poskanzer.