We are pleased to announce the release of ITK 5.4.3, the latest maintenance update for this cross-platform, open-source toolkit supporting N-dimensional scientific image analysis with spatially-aware algorithms. 
This patch release addresses several key issues identified since ITK 5.4.2 while maintaining API stability.
Highlights
As a maintenance update following 5.4.2, version 5.4.3 incorporates critical improvements including:
- Bug Fixes: Resolved issues affecting the default number of threads, particularly in multi-threaded image processing pipelines where thread limits were not respected, and corrected the b-spline size calculation for closed parametric dimensions, ensuring accurate interpolation in applications such as 3D image registration and deformation modeling.
- License Fixes: Removed unused VNL Netlib rpoly files to ensure compliance with our Apache 2.0 licensing requirements.
- Software Guide Updates: Spelling corrections for the ITK Software Guide.
- Doxygen Documentation: Updated Doxygen documentation to reflect the latest changes and improvements in ITK, including links to the ReadTheDocs site.
- Remote Module Updates: Improvements to the
LabelErodeDilateandMeshToPolyDataremote modules, including bug fixes and enhancements.
A full list of changes can be found in the changelog below.
Versioning Note
For comprehensive details on ITK 5.4.0, please review the ITK 5.4.0 Release Notes.
Download
Python Packages
Install ITK Python packages with:
pip install itk
Guide and Textbook
Library Sources
Testing Data
Unpack optional testing data in the same directory where the Library Source is unpacked.
Checksums and Signatures
Congratulations
Congratulations and thank you to everyone who contributed to this release.
What’s Next
ITK 6 Preparation
The development community is currently focused on delivering ITK 6, a major modernization release featuring:
- Architectural upgrades for contemporary C++ development
- Enhanced template metaprogramming capabilities
- Streamlined build system configurations
Early access builds (alpha/beta releases) will become available during ongoing 5.4.x maintenance, enabling parallel evaluation of new features while maintaining production stability.
5.4 Maintenance Commitment
We remain dedicated to supporting current users through:
- Regular security and regression patches
- Critical bug resolution
- Platform compatibility updates
Enjoy ITK!
ITK Changes Since v5.4.2
Bradley Lowekamp (2):
Enhancements
- Use get_schedaffin to determine number of threads (50ab3e0f6e)
Bug Fixes
- Update LabelErodeDilate remote module (ea1ee3a961)
Dženan Zukić (1):
Documentation Updates
- Remove duplicate new author name (Matthieu LAURENDEAU) (6d82d2bd8f)
Matthew McCormick (10):
Enhancements
- Bump ITK version to 5.4.3 (0913f2a962)
Documentation Updates
- Update maintenance branch for 5.4 series (146bc6de06)
- Point to RTD Doxygen documentation, ITKDoxygen Docker build (8ba1cfc8f2)
- Update Doxygen class links to use ReadTheDocs (d3189c245e)
- Update versioned Doxygen links to point to ReadTheDocs (ce4fa184e8)
- ITK 5.4.0 release notes (f2852f6ee9)
- Add ITK 5.4.2 release notes (f817e2f775)
Platform Fixes
- Bump MeshToPolyData Remote Module to 2024-03-14 main (7366509c1c)
Bug Fixes
- Remove VNL Netlib rpoly files (6894a1715c)
- Clamp GlobalDefault threads with GlobalMaximum with initialization (7e485eac71)
Simon Rit (1):
Bug Fixes
- Remove check on WrapITK.pth existence in itk_python_add_test (71d5cce482)
Nick Tustison (1):
Bug Fixes
- Incorrect size for closed parametric dimension. (0dd02ac9f1)
ITK Software Guide Changes Since v5.4.2
Matthew McCormick (1):
Enhancements
- Bump ITK to v5.4.3 (0db3df8)
albert-github (1):
Documentation Updates
- Spelling corrections (5849c78)
Remote Module Changes Since v5.4.2
LabelErodeDilate:
Bradley Lowekamp (4):
Bug Fixes
- Addressed memory leak of progress object (05a0a1c)
- Address uninitialized value (921aaab)
- Fix Valgrind defect with uninitialized array in doOneDimensionErode (b9567df)
Miscellaneous Changes
- Update CI infrastructure to use 5.4.2 infrastructure (c9f9037)
Hans Johnson (4):
Enhancements
Style Changes
- Add itkVirtualGetNameOfClassMacro + itkOverrideGetNameOfClassMacro (6a892cd)
- Update to match clang-format-19 from ITK (32e7773)
Jon Haitz Legarreta Gorroño (12):
Enhancements
- Transition project configuration to
pyproject.toml(8197f14) - Initialize all arrays in
LabelSetUtils.hfile (108b0ba)
Platform Fixes
- Bump to minimum CMake 3.16.3 (f247673)
Style Changes
- Conform to ITK style guidelines in local variable naming (61c7a93)
- Do no use
m_to start function parameter names (c347f23) - Use medial capitals for variable naming in C++ code (518fab1)
- Use
ITK_TRY_EXPECT_NO_EXCEPTIONmacro in tests (5f37494) - Make the input argument checking be the first task in tests (1a5febf)
- Conform to ITK style guidelines in test arg check (7f9ffc7)
- Remove unnecessary brackets around
EXIT_FAILURE(02de4bd) - Remove unreachable
breakafterreturnstatement (0fbfa1c) - Remove unnecessary/empty comment statements in tests (276b195)
MeshToPolyData:
Dženan Zukić (1):
Platform Fixes
- ITK_DISALLOW_COPY_AND_ASSIGN → ITK_DISALLOW_COPY_AND_MOVE (b866a68)
Hans Johnson (7):
Enhancements
- Use latest actions, do not pin to latest version (8aed3c7)
- Use tag v5.4.2 for the build packages tags (9c0209b)
Style Changes
- Add itkVirtualGetNameOfClassMacro + itkOverrideGetNameOfClassMacro (c3c0006)
- Replace itkStaticConstMacro with static constexpr (86435bd)
- CoordRepType → CoordinateType code readability (d90e542)
- Update to match clang-format-19 from ITK (6aa2abf)
- Fix KWStyleError (597c780)
Jon Haitz Legarreta Gorroño (1):
Platform Fixes
- Bump to minimum CMake 3.16.3 (97c575f)
Matt McCormick (12):
Enhancements
- Bump itk-wasm to 1.0.0-b.173 (08779a7)
- Bump itk-wasm version to 1.0.0-b.175 (254a24d)
- Add VTK C++ conversion example (8153ecc)
- Update ITK to 5.4.0 (4ce9813)
- Bump wasm package version to 1.1.1 (a9d1fd7)
- Bump pnpm to 10.6.2 (bd893e4)
- Update pyproject.toml for 0.11.1 (8941ee1)
Documentation Updates
- Lines to Vertices in method description (ff3cc60)
Platform Fixes
- Provide backwards compatible CoordRepType in itk::PolyData (c9e0aba)
- Update wasm for ITK 5.4.2 (1c2a0b5)
Bug Fixes
- Update Python package version to 0.11.0 (5e8de5d)
- Support Variable-Length-Vector in mesh-to-polydata (e9b30dc)