Netpbm formats

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File Format
Name Netpbm formats
Extension(s) .pbm, .pgm, .ppm, .pnm
MIME Type(s) image/x-portable-anymap, others
PRONOM fmt/408, others
Released 1988

The Netpbm formats are a family of simple raster image file formats, associated with the Netpbm library and suite of image processing utilities.



  • PBM (portable bitmap) is a bi-level image format.
  • PGM (portable graymap) is a grayscale image format.
  • PPM (portable pixmap) is a color image format.
  • PNM (portable anymap) is a collective name for PBM, PGM, and PPM. A .pnm file may use any of those formats.
  • PAM: Refer to PAM (Portable Arbitrary Map). Although PAM is one of the Netpbm formats, it's different enough that it's best documented in a separate article.

Identifiers and Identification

Each file begins with two ASCII characters, which serve as a signature.

The PBM, PGM, and PPM formats come in two varieties: a text (or "plain" or "ASCII") format, and a binary (or "raw") format.

Format Signature PRONOM MIME type
PBM, text P1 x-fmt/164 image/x-portable-bitmap, image/x-portable-anymap
PBM, binary P4 fmt/409
PGM, text P2 fmt/407 image/x-portable-graymap, image/x-portable-anymap
PGM, binary P5 fmt/406
PPM, text P3 x-fmt/178 image/x-portable-pixmap, image/x-portable-anymap
PPM, binary P6 fmt/408

See also



The PBM/PGM/PPM/PNM formats are widely supported. Software listed here has been arbitrarily selected.

Sample files


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