SimpleITK 2.0 Release Candidate 3


Announcing the SimpleITK 2.0 Release Candidate 3!

This is anticipated to be the last release candidate before the 2.0 final. Users and developers are encouraged to test the RC before the final release and report issues, bugs, and any significant compatibility problems.

Additional release notes can be found in prior candidates:

Installing SimpleITK

Complete instructions on getting started with SimpleITK including downloading binaries or building SimpleITK can be found on the SimpleITK Read the Docs web page.

Python Binary Downloads

  • Python binary wheels are available for download. It is important to have the latest version of pip for correct wheel compatibility and installation. To install the latest SimpleITK package from GitHub releases:
python -m pip install --upgrade pip
python -m pip install --pre SimpleITK --find-links

Anaconda Binary Downloads

Conda packages are available from Anaconda Cloud on the SimpleITK channel. These can be installed with:

conda install -c simpleitk/label/dev simpleitk

Release Notes

API and Compatibility Changes

  • The environment variables related to the Show method are only checked once. The Show method now is a wrapper for the ImageViewer class, and the behavior changed. The SITK_SHOW_EXTENSION and SITK_SHOW_COMMAND environment variables if defined initialize the corresponding global defaults only the first time accessed. The environment variables SITK_COLOR_COMMAND and SITK_SHOW_3D_COMMAND are removed as the ImageViewer class allows for direct configuration of the command.

New Features

  • Rewrote Show to use ImageViewer class.
  • Added “~/Application” path to ImageView application search path for Mac.
  • Add custom Python procedures or DiscreteGaussian, SmoothingRecursiveGaussian, ReadImage and WriteImage to support keyword arguments.
  • Add to the WriteImage Python procedure the keyword only arguments imageIO and compressor.
  • Use NPasteImageFilter from the SimpleITKFilters remote ITK module to replace PasteImageFilter.
  • Add to SimpleITK’s PasteImageFilter:
    • DestinationSkipAxes parameter
    • Support for pasting lower dimension to higher dimension image e.g 2D slice into 3D volume
    • Ability to use a constant value as input instead of image
  • Add Python __setitem__ for [] operator support:
    • assignment constant to a sliced indexed region
    • assignment of lower dimension image to matching sliced indexed region
  • Add method to ImageFileReader::GetImageIOFromFileName get the ITK ImageIO automatically used for file.
  • Update superbuild Swig version to 4.0.2.

Bug Fixes

  • Fix the ImageRegistrationMethod exception to use GetPixelIDTypeAsString
  • Update ndarray.tostring to tobyte ( tostring deprecated in numpy 1.19.0 )


  • Update doc strings for Python and JAVA from JSON filter descriptions.
  • Update examples to use slice based assignment instead of PasteImageFilter.
  • Update the tutorials page.
  • Update FAQ.
  • Improve WriteImage Doxygen documentation.
  • Update RTD Show procedure documentation.
  • Add custom HTML Doxygen header with dynamic timestamp insertion, and privacy policy.
  • Add procedural example to IO page.
  • Updating the main Doxygen page.


  • Address signed to unsigned comparison compiler warnings.
  • Fix PYTHON_EXECUTABLE being undefined in CMake for Doxygen.
  • Add Doxygen MathJAX URL as CMake option.


  • Test the ImageViewer class and Show procedure.
  • Update and add more testing for Python ImageRead and ImageWrite procedures.
  • Prefer using absolute imports in Python.