pgm
grayscale image format in the Netpbm family
TLDR
View PGM format info
$ pamfile [image.pgm]
Convert JPEG to PGM$ jpegtopnm [image.jpg] | ppmtopgm > [output.pgm]
Create PGM from text$ echo "P2 3 2 255 0 128 255 64 192 32" > [output.pgm]
Display PGM image$ display [image.pgm]
SYNOPSIS
PGM format specification and related utilities
DESCRIPTION
PGM (Portable Graymap) is a grayscale image format in the Netpbm family. It stores images as grayscale values from 0 (black) to maxval (white).
Simple ASCII or binary format, easy to read and write programmatically.
FORMAT
$ P2 # ASCII format (P5 for binary)
width height
maxval # Maximum gray value (usually 255)
pixel_values # Space-separated (ASCII) or raw (binary)
width height
maxval # Maximum gray value (usually 255)
pixel_values # Space-separated (ASCII) or raw (binary)
EXAMPLE FILE
$ P2
# comment
3 2
255
0 128 255
64 192 32
# comment
3 2
255
0 128 255
64 192 32
CONVERSIONS
$ # JPEG to PGM
jpegtopnm photo.jpg | ppmtopgm > photo.pgm
# PNG to PGM
pngtopam image.png | pamtopnm | ppmtopgm > image.pgm
# PGM to PNG
pnmtopng image.pgm > image.png
jpegtopnm photo.jpg | ppmtopgm > photo.pgm
# PNG to PGM
pngtopam image.png | pamtopnm | ppmtopgm > image.pgm
# PGM to PNG
pnmtopng image.pgm > image.png
CAVEATS
ASCII format is larger but human-readable. Binary more efficient. Part of Netpbm toolkit.
HISTORY
PGM was designed by Jef Poskanzer as part of the Netpbm (formerly Pbmplus) toolkit for image manipulation.