PGM (.pgm)

Background & Context

    • MIME type: image/x-portable-graymap
    • PGM grayscale raster image format.
    • Member of the Portable family of image formats.
    • Related to PBM and PPM.
    • Implements a subset of the PNM format.
    • Native format of the Netpbm graphics software package.
    • Primarily used as an intermediate file format on Unix systems.
    • PGM is an acronym for Portable Gray Map.
    • ASCII or binary format.
    • Stores raster images formatted as plain text, representing each pixel as an 8-bit gray level.
    • Developed in 1988 as part of the Pbmplus package.

Import & Export

  • Import["file.pgm"] imports a PGM file as an image.
  • Import["file.pgm",elem] imports the specified element from a PGM file.
  • The import format can be specified with Import["file","PGM"] or Import["file",{"PGM",elem,…}].
  • Export["file.pgm",expr] exports an image, graphics, or any other expression as a raster image to PGM.
  • Export by default generates binary PGM files.
  • When exporting Wolfram Language graphics or arbitrary expressions to PGM, the resulting image has the same raster size as its displayed form.
  • Image objects are by default exported at their raster size.
  • Because PGM is a raster image format, all fonts are rasterized on export.
  • See the following reference pages for full general information:
  • Import, Exportimport from or export to a file
    CloudImport, CloudExportimport from or export to a cloud object
    ImportString, ExportStringimport from or export to a string
    ImportByteArray, ExportByteArrayimport from or export to a byte array

Notebook Interface

  • In the notebook front end, Insert ▶ Picture and the Open menu allow import of a PGM file into a cell.
  • Save Selection As exports the selected part of a notebook as a PGM file.

Import Elements

  • General Import elements:
  • "Elements" list of elements and options available in this file
    "Summary"summary of the file
    "Rules"list of rules for all available elements
  • Data representation elements:
  • "Data"array of grayscale values
    "Graphics"Graphics object representing an image
    "Image"raster image, given as an Image object
  • Import and Export by default use the "Image" element for PGM files.
  • Advanced Import elements:
  • "BitDepth"bits used to represent each color channel in the file
    "Channels"the number of color channels used in the file
    "ColorSpace"color space of the image
    "DataType"data type used for storing pixel elements
    "ImageSize"raster dimensions
    "Summary"summary of the file

Options

Examples

Basic Examples  (4)

Import a PGM file:

Summary of an image:

Export a gray-level image to PGM:

Export arbitrary graphics to the PGM format: