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Read and write Netpbm files

Project description

Netpbmfile is a Python library to read and write image files in the Netpbm format as specified at

The following Netpbm and Portable FloatMap formats are supported:

  • PBM (bi-level)
  • PGM (grayscale)
  • PPM (color)
  • PAM (arbitrary)
  • XV thumbnail (RGB332, read-only)
  • Pf (float32 grayscale, read-only)
  • PF (float32 RGB, read-only)
  • PF4 (float32 RGBA, read-only)
  • PGX (signed grayscale, read-only)

No gamma correction is performed. Only one image per file is supported.

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

Author:Christoph Gohlke
Organization:Laboratory for Fluorescence Dynamics, University of California, Irvine
License:BSD 3-Clause


This release has been tested with the following requirements and dependencies (other versions may work):


Add type hints. Support reading PF4 RGBA FloatMaps. Drop support for Python 3.7 and numpy < 1.19 (NEP29).
Fix unclosed file warnings. Support reading PGX JPEG2000 reference images.
Disallow comments after last value in PNM headers.
Remove support for Python 3.6 (NEP 29). Support os.PathLike file names.
Fix reading tightly packed P1 format and ASCII data with inline comments. Remove support for Python 2.7 and 3.5. Update copyright.
Move into netpbmfile package.
Support reading Portable FloatMaps. Style fixes.
Use ‘fromdata’ classmethod to initialize from data. Support ‘with’ statement. Scale RGB images to maxval for display. Make keyword arguments explicit. Support numpy 1.10.


Save a numpy array to a Netpbm file in grayscale format:

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

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

>>> image = imread('_tmp.pgm')
>>> assert numpy.all(image == data)

Access meta and image data in a Netpbm file:

>>> with NetpbmFile('_tmp.pgm') as pgm:
...     pgm.axes
...     pgm.shape
...     pgm.dtype
...     pgm.maxval
...     pgm.magicnum
...     image = pgm.asarray()
(2, 2)

To view the image stored in a Netpbm file from a command line, run python -m netpbmfile _tmp.pgm.

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