netpbmfile 2022.9.12

Read and write Netpbm files

Netpbmfile is a Python library to read and write image files in the Netpbm format as specified at http://netpbm.sourceforge.net/doc/.

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

License:

BSD 3-Clause

Version:

2022.9.12

Requirements

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

• CPython 3.8.10, 3.9.13, 3.10.7, 3.11.0rc2

• NumPy 1.22.4

• Matplotlib 3.5.3 (optional)

Revisions

2022.9.12

• Allow space after token value in PAM.

• Update metadata.

2022.2.2

• Add type hints.

• Support reading PF4 RGBA FloatMaps.

• Drop support for Python 3.7 and numpy < 1.19 (NEP29).

2021.6.6

• Fix unclosed file warnings.

• Support reading PGX JPEG2000 reference images.

2020.10.18

• Disallow comments after last value in PNM headers.

2020.9.18

• Remove support for Python 3.6 (NEP 29).

• Support os.PathLike file names.

2020.1.1

• Fix reading tightly packed P1 format and ASCII data with inline comments.

• Remove support for Python 2.7 and 3.5.

• Update copyright.

2018.10.18

• Move netpbmfile.py into netpbmfile package.

2018.02.18

• Support reading Portable FloatMaps.

• Style fixes.

2016.02.24

• 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.

Examples

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()
'YX'
(2, 2)
dtype('>u2')
65535
b'P5'

View the image stored in a Netpbm file from a command line:

python -m netpbmfile _tmp.pgm