netpbmfile 2026.7.25

Read and write Netpbm files

Netpbmfile is a Python library to read and write image files in the Netpbm or related formats:

• PBM (Portable Bit Map): P1 (text) and P4 (binary)

• PGM (Portable Gray Map): P2 (text) and P5 (binary)

• PPM (Portable Pixel Map): P3 (text) and P6 (binary)

• PNM (Portable Any Map): shorthand for PBM, PGM, and PPM collectively

• PAM (Portable Arbitrary Map): P7, bilevel, gray, rgb, and arbitrary depths

• PGX (Portable Graymap Signed): PG, signed grayscale

• PFM (Portable Float Map): Pf (gray), PF (rgb), and PF4 (rgba), read-only

• XV thumbnail: P7 332 (rgb332), read-only

The Netpbm formats are specified at https://netpbm.sourceforge.net/doc/.

The PGX format is specified in ITU-T Rec. T.803.

No gamma correction or scaling is performed.

Author:

Christoph Gohlke

License:

BSD-3-Clause

Version:

2026.7.25

DOI:

10.5281/zenodo.17903402

Quickstart

Install the netpbmfile package and all dependencies from the Python Package Index:

python -m pip install -U "netpbmfile[all]"

See Examples for using the programming interface.

Source code and support are available on GitHub.

Requirements

This revision was tested with the following requirements and dependencies (other versions may work):

• CPython 3.12.10, 3.13.14, 3.14.6, 3.15.0b4 64-bit

• Numpy 2.5.1

Revisions

2026.7.25

• Drop support for Python 3.11 and numpy 2.0 (SPEC0), support Python 3.15.

2026.1.29

• Fix code review issues.

2026.1.8

• Improve code quality.

2025.12.12

• Drop support for Python 3.10, support Python 3.14.

2025.5.8

• Remove doctest command line option.

2025.1.1

• Improve type hints.

• Drop support for Python 3.9, support Python 3.13.

2024.5.24

• …

Refer to the CHANGES file for older revisions.

Examples

Write a numpy array to a Netpbm file in grayscale binary format:

>>> import numpy
>>> data = numpy.array([[0, 1], [65534, 65535]], dtype=numpy.uint16)
>>> imwrite('_tmp.pgm', data)

Read the image data from a Netpbm file as numpy array:

>>> image = imread('_tmp.pgm')
>>> numpy.testing.assert_equal(image, data)

Access meta and image data in a Netpbm file:

>>> with NetpbmFile('_tmp.pgm') as pgm:
...     pgm.magicnumber
...     pgm.axes
...     pgm.shape
...     pgm.dtype
...     pgm.maxval
...     pgm.asarray().tolist()
...
'P5'
'YX'
(2, 2)
dtype('>u2')
65535
[[0, 1], [65534, 65535]]

View the image and metadata in the Netpbm file from the command line:

$ python -m netpbmfile _tmp.pgm