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<A NAME="PAGENUM-353"><P>Page 353</P></A>
<P><B>
DESCRIPTION
</B>
</P>
<P>pbmlife reads a portable bitmap as input, applies the Rules of Life to it for one generation, and produces a portable bitmap
as output.
</P>
<P>A white pixel in the image is interpreted as a live beastie, and a black pixel as an empty space.
</P>
<P><B>
SEE ALSO
</B>
</P>
<!-- CODE SNIP //-->
<PRE>pbm(5)
</PRE>
<!-- END CODE SNIP //-->
<P><B>
AUTHOR
</B>
</P>
<P>Copyright " 1988, 1991 by Jef Poskanzer
</P>
<P>21 February 1991
</P>
<H3><A NAME="ch01_ 205">
pbmmake
</A></H3>
<P>pbmmake—Create a blank bitmap of a specified size
</P>
<P><B>
SYNOPSIS
</B>
</P>
<!-- CODE SNIP //-->
<PRE>
pbmmake [-white|-black|-gray ] width height
</PRE>
<!-- END CODE SNIP //-->
<P><B>
DESCRIPTION
</B>
</P>
<P>pbmmake produces a portable bitmap of the specified width and height. The color defaults to
white.
</P>
<P><B>
OPTIONS
</B>
</P>
<P>In addition to the usual -white and -black, this program implements
-gray. This gives a simple 50 percent gray pattern
with 1's and 0's alternating.
</P>
<P>All flags can be abbreviated to their shortest unique prefix.
</P>
<P><B>
SEE ALSO
</B>
</P>
<!-- CODE SNIP //-->
<PRE>pbm(5), ppmmake(1)
</PRE>
<!-- END CODE SNIP //-->
<P><B>
AUTHOR
</B>
</P>
<P>Copyright " 1989 by Jef Poskanzer
</P>
<P>22 February 1989
</P>
<H3><A NAME="ch01_ 206">
pbmmask
</A></H3>
<P>pbmmask—Create a mask bitmap from a regular bitmap
</P>
<P><B>
SYNOPSIS
</B>
</P>
<!-- CODE SNIP //-->
<PRE>
pbmmask [-expand][pbmfile]
</PRE>
<!-- END CODE SNIP //-->
<P><B>
DESCRIPTION
</B>
</P>
<P>pbmmask reads a portable bitmap as input and creates a corresponding mask bitmap and writes it out.
</P>
<P>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 white and black where the figure is black.
</P>
<A NAME="PAGENUM-354"><P>Page 354</P></A>
<P>This lets you do a masked paste like this, for objects with a black background:
</P>
<!-- CODE SNIP //-->
<PRE>
pbmmask obj > objmask
pnmpaste < dest -and objmask <x><y>|pnmpaste -or obj <x><y>
</PRE>
<!-- END CODE SNIP //-->
<P>For objects with a white background, you can either invert them or add a step:
</P>
<!-- CODE SNIP //-->
<PRE>
pbmmask obj > objmask
pnminvert objmask | pnmpaste -and obj 0 0 > blackback
pnmpaste < dest -and objmask <x><y>|pnmpaste -or blackback <x><y>
</PRE>
<!-- END CODE SNIP //-->
<P>Note that this three-step version works for objects with black backgrounds, too, if you don't care about the wasted time.
</P>
<P>You can also use masks with graymaps and pixmaps, using the
pnmarith tool. For instance:
</P>
<!-- CODE //-->
<PRE>
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
</PRE>
<!-- END CODE //-->
<P>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.
</P>
<P><B>
OPTIONS
</B>
</P>
<P>-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…)
</P>
<P><B>
SEE ALSO
</B>
</P>
<!-- CODE SNIP //-->
<PRE>pnmpaste(1), pnminvert(1), pbm(5), pnmarith(1), pnmsmooth(1)
</PRE>
<!-- END CODE SNIP //-->
<P><B>
AUTHOR
</B>
</P>
<P>Copyright " 1988 by Jef Poskanzer
</P>
<P>8 August 1989
</P>
<H3><A NAME="ch01_ 207">
pbmpscale
</A></H3>
<P>pbmpscale—Enlarge a portable bitmap with edge smoothing
</P>
<P><B>
SYNOPSIS
</B>
</P>
<!-- CODE SNIP //-->
<PRE>
pbmpscale N [ pbmfile ]
</PRE>
<!-- END CODE SNIP //-->
<P><B>
DESCRIPTION
</B>
</P>
<P>pbmpscale reads a portable bitmap as input and outputs a portable bitmap enlarged N times. Enlargement is done by
pixel replication, with some additional smoothing of corners and edges.
</P>
<P><B>
SEE ALSO
</B>
</P>
<!-- CODE SNIP //-->
<PRE>pnmenlarge(1), ppmscale(1), pbm(5)
</PRE>
<!-- END CODE SNIP //-->
<P><B>
AUTHOR
</B>
</P>
<P>Copyright " 1990 by Angus Duggan. Copyright
" 1989 by Jef Poskanzer.
</P>
<P><B>
NOTES
</B>
</P>
<P>pbmpscale works best for enlargements of 2. Enlargements greater than 2 should be done by as many enlargements of 2
as possible, followed by an enlargement by the remaining factor.
</P>
<A NAME="PAGENUM-355"><P>Page 355</P></A>
<H3><A NAME="ch01_ 208">
pbmreduce
</A></H3>
<P>pbmreduce—Read a portable bitmap and reduce it N times
</P>
<P><B>
SYNOPSIS
</B>
</P>
<!-- CODE SNIP //-->
<PRE>
pbmreduce [-floyd|-fs|-threshold ][-value val] N [pbmfile]
</PRE>
<!-- END CODE SNIP //-->
<P><B>
DESCRIPTION
</B>
</P>
<P>pbmreduce reads a portable bitmap as input, reduces it by a factor of
N, and produces a portable bitmap as output.
</P>
<P>pbmreduce duplicates a lot of the functionality of
pgmtopbm; you could do something like pnmscale |
pgmtopbm, but pbmreduce is a lot faster.
</P>
<P>pbmreduce can be used to "re-halftone" an image. Say you have a scanner that only produces black and white, not
grayscale, and it does a terrible job of halftoning (most black-and-white scanners fit this description). One way to fix the halftoning
is to scan at the highest possible resolution, say 300dpi, and then reduce by a factor of three or so using
pbmreduce.You can even correct the brightness of an image, by using the
-value flag.
</P>
<P><B>
OPTIONS
</B>
</P>
<P>By default, the halftoning after the reduction is done via boustrophedonic Floyd-Steinberg error diffusion; however, the
-threshold flag can be used to specify simple thresholding. This gives better results when reducing line drawings.
<P>The -value flag alters the thresholding value for all quantizations. It should be a real number between 0 and 1. Above
0.5 means darker images; below 0.5 means lighter.
</P>
<P>All flags can be abbreviated to their shortest unique prefix.
</P>
<P><B>
SEE ALSO
</B>
</P>
<!-- CODE SNIP //-->
<PRE>pnmenlarge(1), pnmscale(1), pgmtopbm(1), pbm(5)
</PRE>
<!-- END CODE SNIP //-->
<P><B>
AUTHOR
</B>
</P>
<P>Copyright " 1988 by Jef Poskanzer
</P>
<P>2 August 1989
</P>
<H3><A NAME="ch01_ 209">
pbmtext
</A></H3>
<P>pbmtext—Render text into a bitmap
</P>
<P><B>
SYNOPSIS
</B>
</P>
<!-- CODE SNIP //-->
<PRE>
pbmtext [_font fontfile][_builtin fontname][text]
</PRE>
<!-- END CODE SNIP //-->
<P><B>
DESCRIPTION
</B>
</P>
<P>pbmtext takes the specified text, either a single line from the command line or multiple lines from standard input, and
renders it into a bitmap.
</P>
<P><B>
OPTIONS
</B>
</P>
<P>By default, pbmtext uses a built-in font called bdf (about a 10-point Times Roman font). You can use a fixed-width font
by specifying _builtin fixed.
</P>
<P>You can also specify your own font with the -font
flag. The fontfile is either a BDF file from the X Window System or
a PBM file.
</P>
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