PBMB Files
Portable Bit Map (binary)

PBMB is a data directory which contains examples of the binary version of the portable bitmap PBM format, a lowest common denominator monochrome file format. It was originally designed to make it reasonable to mail bitmaps between different types of machines. Now it serves as the common language of a large family of bitmap conversion filters. The definition is as follows:

• the typical file extension is ".pbm", but an extension of ".pnm" is also occasionally used.
• A "magic number" for identifying the file type. A binary PBMB file's magic number is the two characters "P4".
• Whitespace (blanks, TABs, CRs, LFs).
• A width, formatted as ASCII characters in decimal.
• Whitespace.
• A height, again in ASCII decimal.
• Whitespace. (It may be the case that this is required to be a single character of whitespace, usually a new line.)
• Width * height bits, stored 8 bits per byte, high bit first and low bit last, starting at the top-left corner of the bitmap, proceeding in normal English reading order.

Binary PBM File Characteristics:

• binary
• black and white
• 2D
• No compression
• 1 image

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Related Data and Programs:

PBMA, a data directory which contains examples of ASCII Portable Bit Map files.

PGMB, a data directory which contains examples of binary Portable Gray Map files.

PPMB, a data directory which contains examples of binary Portable Pixel Map files.

Reference:

1. the NETPBM homepage.

Sample Files:

• apollonian_gasket.pbm, a 600 wide by 600 high image of an Apollonian gasket.
• apollonian_gasket.png, a PNG image.
• circle.pbm, a circle, drawn on a 200 by 200 grid;
• circle.png, a PNG version.
• dla.pbm, an 800 by 800 image of a structure created by diffusion-limited aggregation.
• dla.png, a PNG version.
• feep.pbm, the example described above, on a 24 by 7 grid;
• feep.png, a PNG version.
• fool.pbm, a screenshot from "The Fool's Errand".
• fool.png, a PNG version.
• gerrymander.pbm, an image of the "Gerry-mander", on a 303 by 325 grid;
• gerrymander.png, a PNG version.
• letter_a.pbm, a capital A, using a 25 by 25 grid.
• letter_a.png, a PNG version.
• math_emporium.pbm, a blueprint of the Math Emporium at Virginia Tech, on a 1376 by 1096 grid.
• math_emporium.png, a PNG version.
• pbmlib.pbm, a file created by PBMLIB.
• pbmlib.png, a PNG version.
• scs.pbm, the letters "SCS", on a grid 136 wide and 82 high.
• scs.png, a PNG version.
• seahorse.pbm, a silhouette of a sea horse, on a grid 2225 wide and 3601 high.
• seahorse.png, a PNG version.
• sierpinski.pbm, an image of the Sierpinksi fractal triangle, on a grid 966 wide and 860 high.
• sierpinski.png, a PNG version.
• washington.pbm, a silhouette of George Washington, on a grid 305 wide and 400 high.
• washington.png, a PNG version.

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