netpbmfile 2023.8.30

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, and rgb

• 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 http://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:

2023.8.30

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 3.9.13, 3.10.11, 3.11.5, 3.12rc

• NumPy 1.25.2

Revisions

2023.8.30

• Fix linting issues.

• Add py.typed marker.

2023.6.15

• Drop support for Python 3.8 and numpy < 1.21 (NEP29).

• Improve type hints.

2023.1.1

• Several breaking changes:

• Rename magicnum to magicnumber (breaking).

• Rename tupltypes to tupltype (breaking).

• Change magicnumber and header properties to str (breaking).

• Replace pam parameter with magicnumber (breaking).

• Move byteorder parameter from NetpbmFile.asarray to NetpbmFile (breaking).

• Fix shape and axes properties for multi-image files.

• Add maxval and tupltype parameters to NetpbmFile.fromdata and imwrite.

• Add option to write comment to PNM and PAM files.

• Support writing PGX and text formats.

• Add Google style docstrings.

• Add unittests.

2022.10.25

• Read multi-image files.

• Fix reading ASCII formats with trailing comments.

• Fix writing maxval=1, depth=1 binary images.

• Use tifffile.imshow for multi-image arrays if installed.

• Change tupltypes to bytes according to specification (breaking).

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

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

>>> 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