Netpbm formats

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File Format
Name Netpbm formats
Ontology
Extension(s) .pbm, .pgm, .ppm, .pnm
MIME Type(s) image/x-portable-anymap, others
PRONOM fmt/408, others
Released 1988
"PBM" redirects here. For another PBM format, see ILBM#PBM.

The Netpbm formats are a family of simple uncompressed raster image file formats, associated with the Netpbm library and suite of image processing utilities. They are designed so that it is straightforward for programmers to import and export them.

Due to their simplicity, the Netpbm formats are often used as "neutral" or "universal" image formats. It's not unusual for an image format's reference software to include a utility to convert to and from one of the Netpbm formats (and perhaps no other formats). Many of these conversion utilities have ultimately been incorporated into the Netpbm software.

Contents

Formats

  • 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 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 types
PBM text P1 x-fmt/164 image/x-portable-bitmap image/x-portable-anymap
binary P4 fmt/409
PGM text P2 fmt/407 image/x-portable-graymap
binary P5 fmt/406
PPM text P3 x-fmt/178 image/x-portable-pixmap
binary P6 fmt/408

Multi-image files

Although the Netpbm formats are usually thought of as single-image formats, the binary formats technically do support multiple images per file. This is accomplished simply by concatenating single-image files together. Such multi-image files are probably not well-supported.

See also

Specifications

Software

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

Sample files

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