pbm(5) pbm(5)
NAME
pbm - portable bitmap file format
DESCRIPTION
The portable bitmap format is a lowest common denominator
monochrome file format. It was originally designed to
make it reasonable to mail bitmaps between different types
of machines using the typical stupid network mailers we
have today. Now it serves as the common language of a
large family of bitmap conversion filters. The definition
is as follows:
- A "magic number" for identifying the file type. A pbm
file's magic number is the two characters "P1".
- Whitespace (blanks, TABs, CRs, LFs).
- A width, formatted as ASCII characters in decimal.
- Whitespace.
- A height, again in ASCII decimal.
- Whitespace.
- Width * height bits, each either '1' or '0', starting at
the top-left corner of the bitmap, proceeding in normal
English reading order.
- The character '1' means black, '0' means white.
- Whitespace in the bits section is ignored.
- Characters from a "#" to the next end-of-line are
ignored (comments).
- No line should be longer than 70 characters.
Here is an example of a small bitmap in this format:
P1
# feep.pbm
24 7
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 1 1 1 1 0 0 1 1 1 1 0 0 1 1 1 1 0 0 1 1 1 1 0
0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 1 0
0 1 1 1 0 0 0 1 1 1 0 0 0 1 1 1 0 0 0 1 1 1 1 0
0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0
0 1 0 0 0 0 0 1 1 1 1 0 0 1 1 1 1 0 0 1 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Programs that read this format should be as lenient as
possible, accepting anything that looks remotely like a
bitmap.
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pbm(5) pbm(5)
There is also a variant on the format, available by set-
ting the RAWBITS option at compile time. This variant is
different in the following ways:
- The "magic number" is "P4" instead of "P1".
- The bits are stored eight per byte, high bit first low
bit last.
- No whitespace is allowed in the bits section, and only a
single character of whitespace (typically a newline) is
allowed after the height.
- The files are eight times smaller and many times faster
to read and write.
SEE ALSO
atktopbm(1), brushtopbm(1), cmuwmtopbm(1), g3topbm(1),
gemtopbm(1), icontopbm(1), macptopbm(1), mgrtopbm(1),
pi3topbm(1), xbmtopbm(1), ybmtopbm(1), pbmto10x(1), pnm-
toascii(1), pbmtoatk(1), pbmtobbnbg(1), pbmtocmuwm(1),
pbmtoepson(1), pbmtog3(1), pbmtogem(1), pbmtogo(1), pbmto-
icon(1), pbmtolj(1), pbmtomacp(1), pbmtomgr(1), pbm-
topi3(1), pbmtoplot(1), pbmtoptx(1), pbmtox10bm(1), pbm-
toxbm(1), pbmtoybm(1), pbmtozinc(1), pbmlife(1), pbm-
make(1), pbmmask(1), pbmreduce(1), pbmtext(1), pbmupc(1),
pnm(5), pgm(5), ppm(5)
AUTHOR
Copyright (C) 1989, 1991 by Jef Poskanzer.
27 September 1991 2