# ITK 5.2.1 has been released!

**URL:** https://discourse.itk.org/t/itk-5-2-1-has-been-released/4336
**Category:** Announcements
**Tags:** python, dask, releases, monai, itk-releases
**Created:** [August 17, 2021, 5:21pm UTC](https://discourse.itk.org/t/itk-5-2-1-has-been-released/4336 "2021-08-17T17:21:53Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![matt.mccormick](https://discourse.itk.org/user_avatar/discourse.itk.org/matt.mccormick/32/7_2.png) [@matt.mccormick](https://discourse.itk.org/u/matt.mccormick)
#### Post date: [August 17, 2021, 5:21pm UTC](https://discourse.itk.org/t/itk-5-2-1-has-been-released/4336/1 "2021-08-17T17:21:54Z")

</div>

# ITK 5.2.1 Release Notes

We are happy to announce the Insight Toolkit (ITK) 5.2.1! 🎉

**Python Packages**

Install [ITK Python packages](https://itkpythonpackage.readthedocs.io/en/latest/Quick_start_guide.html) with:

```auto
pip install --upgrade itk

```

**Guide and Textbook**

- [InsightSoftwareGuide-Book1-5.2.1.pdf](https://github.com/InsightSoftwareConsortium/ITK/releases/download/v5.2.1/InsightSoftwareGuide-Book1-5.2.1.pdf)
- [InsightSoftwareGuide-Book2-5.2.1.pdf](https://github.com/InsightSoftwareConsortium/ITK/releases/download/v5.2.1/InsightSoftwareGuide-Book2-5.2.1.pdf)

**Library Sources**

- [InsightToolkit-5.2.1.tar.gz](https://github.com/InsightSoftwareConsortium/ITK/releases/download/v5.2.1/InsightToolkit-5.2.1.tar.gz)
- [InsightToolkit-5.2.1.zip](https://github.com/InsightSoftwareConsortium/ITK/releases/download/v5.2.1/InsightToolkit-5.2.1.zip)

**Testing Data**

Unpack optional testing data in the same directory where the Library Source is unpacked.

- [InsightData-5.2.1.tar.gz](https://github.com/InsightSoftwareConsortium/ITK/releases/download/v5.2.1/InsightData-5.2.1.tar.gz)
- [InsightData-5.2.1.zip](https://github.com/InsightSoftwareConsortium/ITK/releases/download/v5.2.1/InsightData-5.2.1.zip)

**Checksums**

- [MD5SUMS](https://github.com/InsightSoftwareConsortium/ITK/releases/download/v5.2.1/MD5SUMS)
- [SHA512SUMS](https://github.com/InsightSoftwareConsortium/ITK/releases/download/v5.2.1/SHA512SUMS)

ITK 5.2.1 is a patch release that makes improvements to issues found in the 5.2.0 release. For more details on ITK 5.2, see the [ITK 5.2.0 Release Notes](https://github.com/InsightSoftwareConsortium/ITK/releases/tag/v5.2.0).

This release addresses various issues like improved combination of `itk`’s native thread pool with Python’s `multiprocessing` module in contexts like [MONAI](https://monai.io/) and [Dask](https://dask.org/). Other improvements include more robust label map statistic computation, expanded Python support for additional datatypes, fixes for tube spatial objects when processing with the [TubeTK](https://github.com/InsightSoftwareConsortium/ITKTubeTK) module, support for GCC 11, and compatibility with the C++20 and C++23 standards. A detailed list can be found in the changelog below.

## What’s Next

Join us in the creation of advanced, open source scientific image analysis tools. Take part in the community discussion at [discourse.itk.org](https://discourse.itk.org). Contribute with pull requests, code reviews, and issue discussions in our [GitHub Organization](https://github.com/InsightSoftwareConsortium).

The first release candidate for ITK 5.3, the next feature release, is anticipated in September.

**Enjoy ITK!**

## ITK Changes Since v5.2.0

### Bradley Lowekamp (7):

#### Enhancements

- StatisticsLabelMapFilter use improve integer histogram ([daa2a20f4b](https://github.com/InsightSoftwareConsortium/ITK/commit/daa2a20f4b))
- Add additional testing for zero sized label object ([1fba0db29b](https://github.com/InsightSoftwareConsortium/ITK/commit/1fba0db29b))

#### Bug Fixes

- Register ComposeScaleSkewVersor3DTransform transform ([8c7784d183](https://github.com/InsightSoftwareConsortium/ITK/commit/8c7784d183))
- Add tests demonstration current behavior of histogram based median ([55d0fdfafa](https://github.com/InsightSoftwareConsortium/ITK/commit/55d0fdfafa))
- Fix StatisticsLabelMap median for even number of pixels ([3abace1991](https://github.com/InsightSoftwareConsortium/ITK/commit/3abace1991))
- Fix HDF5 installation with cmake targets ([4ecd711eab](https://github.com/InsightSoftwareConsortium/ITK/commit/4ecd711eab))
- Propagate usage of HDF5 find\_package NO\_MODULE arg to install ([f83a0ba9f4](https://github.com/InsightSoftwareConsortium/ITK/commit/f83a0ba9f4))

### Dženan Zukić (9):

#### Enhancements

- fix Python multi-processing hang on unix ([2370517505](https://github.com/InsightSoftwareConsortium/ITK/commit/2370517505))
- Python wrapping reads VLV pixel type correctly ([4ae3749a61](https://github.com/InsightSoftwareConsortium/ITK/commit/4ae3749a61))
- Add support for long long pixel types to ImageDuplicator wrapping ([278ac68e40](https://github.com/InsightSoftwareConsortium/ITK/commit/278ac68e40))

#### Platform Fixes

- Update KWStyle to fix compile warnings on Ubuntu 20.04 ([32501b4230](https://github.com/InsightSoftwareConsortium/ITK/commit/32501b4230))
- Restore generation of static runtime library on MSVC ([dbb34f96cc](https://github.com/InsightSoftwareConsortium/ITK/commit/dbb34f96cc))
- Update KWStyle’s version to avoid compile errors with C++23 ([3d85fafc77](https://github.com/InsightSoftwareConsortium/ITK/commit/3d85fafc77))
- use WRAP\_ITK\_SCALAR instead of WRAP\_ITK\_REAL in mesh filters ([68944d52d7](https://github.com/InsightSoftwareConsortium/ITK/commit/68944d52d7))

#### Bug Fixes

- add support for long long pixel types in PyBuffer ([ae7079c4fd](https://github.com/InsightSoftwareConsortium/ITK/commit/ae7079c4fd))

#### Miscellaneous Changes

- Revert “COMP: Use CMake 3.18.4 in macOS CI builds” ([07176983ed](https://github.com/InsightSoftwareConsortium/ITK/commit/07176983ed))

### GDCM Upstream (1):

#### Miscellaneous Changes

- GDCM 2021-06-07 (4404b770) ([47e97596b9](https://github.com/InsightSoftwareConsortium/ITK/commit/47e97596b9))

### Lee Newberg (3):

#### Enhancements

- Propagate StatisticsLabelMapFilter’s default NumberOfBins ([509751d5f5](https://github.com/InsightSoftwareConsortium/ITK/commit/509751d5f5))
- Wrap itkAdaptiveHistogramEqualizationImageFilter for Python. ([974c63db99](https://github.com/InsightSoftwareConsortium/ITK/commit/974c63db99))

#### Bug Fixes

- Ellipsis is not iterable ([ca0690069a](https://github.com/InsightSoftwareConsortium/ITK/commit/ca0690069a))

### Matt McCormick (16):

#### Enhancements

- Update CastXML source builds to v0.4.3, LLVM 11.1.0 ([67fdd3067e](https://github.com/InsightSoftwareConsortium/ITK/commit/67fdd3067e))
- Add CastXML binary for macOS arm64 ([fde7fa6ce8](https://github.com/InsightSoftwareConsortium/ITK/commit/fde7fa6ce8))
- Add Linux arm64 CastXML binaries ([42aa3be3e4](https://github.com/InsightSoftwareConsortium/ITK/commit/42aa3be3e4))
- Bump the ITK CMake version to 5.1.0 ([9f3fc5dd12](https://github.com/InsightSoftwareConsortium/ITK/commit/9f3fc5dd12))
- Content link synchronization for ITK 5.2.1 ([8be208ee1f](https://github.com/InsightSoftwareConsortium/ITK/commit/8be208ee1f))

#### Platform Fixes

- Backport CastXML arm64 Eigen support ([a3996fe99a](https://github.com/InsightSoftwareConsortium/ITK/commit/a3996fe99a))
- Do not add IPO to Python wrapping if not supported ([3d2e898400](https://github.com/InsightSoftwareConsortium/ITK/commit/3d2e898400))
- Only use np.float128 when available ([1237a57a3d](https://github.com/InsightSoftwareConsortium/ITK/commit/1237a57a3d))
- Make floating point exceptions a no-op with MUSL, Linux, ARMv8 ([0afa3f06a1](https://github.com/InsightSoftwareConsortium/ITK/commit/0afa3f06a1))
- Use numpy==1.20.3 for CI testing ([b667ce4d25](https://github.com/InsightSoftwareConsortium/ITK/commit/b667ce4d25))
- Use mallinfo2 when available ([f540091c6a](https://github.com/InsightSoftwareConsortium/ITK/commit/f540091c6a))
- Add missing template export macro to SLICImageFilter ([c3e40927f8](https://github.com/InsightSoftwareConsortium/ITK/commit/c3e40927f8))

#### Bug Fixes

- Add vnl\_vector\_from\_array to extras **all** ([3f8b14be54](https://github.com/InsightSoftwareConsortium/ITK/commit/3f8b14be54))
- Do not create global multiprocessing RLock ([cfdb5023a8](https://github.com/InsightSoftwareConsortium/ITK/commit/cfdb5023a8))
- Support double colons in Changelog commit summary ([62804d09e9](https://github.com/InsightSoftwareConsortium/ITK/commit/62804d09e9))

#### Style Changes

- Apply black to AuthorsChangesSince.py script ([7504f6e45c](https://github.com/InsightSoftwareConsortium/ITK/commit/7504f6e45c))

### Niels Dekker (1):

#### Bug Fixes

- `Similarity3DTransform::SetScale` should recompute `m_Offset` ([dd893faf8a](https://github.com/InsightSoftwareConsortium/ITK/commit/dd893faf8a))

### Pablo Hernandez-Cerdan (1):

#### Enhancements

- Increase hook-max-size for next GDCM update ([f913c0b6ed](https://github.com/InsightSoftwareConsortium/ITK/commit/f913c0b6ed))

### Stephen R. Aylward (5):

#### Enhancements

- Updated SpatialObject wrapping to support CONST\_POINTER ([28cb8507fd](https://github.com/InsightSoftwareConsortium/ITK/commit/28cb8507fd))

#### Platform Fixes

- Update SpatialObjects to correct const-ness ([903f7c152e](https://github.com/InsightSoftwareConsortium/ITK/commit/903f7c152e))

#### Bug Fixes

- SpatialObject writes object color ([3bf34f6cc5](https://github.com/InsightSoftwareConsortium/ITK/commit/3bf34f6cc5))
- TubeSpatialObject missing CopyInformation ([3060a6d1e5](https://github.com/InsightSoftwareConsortium/ITK/commit/3060a6d1e5))
- TubeSpatialObject didn’t preserver Artery flag ([2c3d27c9ee](https://github.com/InsightSoftwareConsortium/ITK/commit/2c3d27c9ee))

### Thompson, Darren (IM&T, Clayton) (2):

#### Platform Fixes

- Removed constructor template parameters from the VNL library ([f27ab3f91f](https://github.com/InsightSoftwareConsortium/ITK/commit/f27ab3f91f))
- Removed constructor template parameters from itkSmapsFileParser ([4c320b1d49](https://github.com/InsightSoftwareConsortium/ITK/commit/4c320b1d49))

### Tom Birdsong (1):

#### Enhancements

- Add `float` wrappings for itkSymmetricSecondRankTensor ([5378dae447](https://github.com/InsightSoftwareConsortium/ITK/commit/5378dae447))

### VXL Maintainers (1):

#### Miscellaneous Changes

- VXL 2021-07-19 (22f874db) ([2e42c87c6e](https://github.com/InsightSoftwareConsortium/ITK/commit/2e42c87c6e))

## ITK Software Guide Changes Since v5.2.0

### Jon Haitz Legarreta Gorroño (3):

#### Documentation Updates

- Adapt enum section to strongly typed enums ([088a010](https://github.com/InsightSoftwareConsortium/ITKSoftwareGuide/commit/088a010))
- Add `long long` specifier C++ and mangling types ([cf51385](https://github.com/InsightSoftwareConsortium/ITKSoftwareGuide/commit/cf51385))

#### Style Changes

- Use `itkNameOfTestExecutableMacro` macro for test names ([e116243](https://github.com/InsightSoftwareConsortium/ITKSoftwareGuide/commit/e116243))

### Matt McCormick (3):

#### Enhancements

- Update ITK to v5.2.0 ([d5dab33](https://github.com/InsightSoftwareConsortium/ITKSoftwareGuide/commit/d5dab33))
- Update ITK version to 5.2.1 ([81c741c](https://github.com/InsightSoftwareConsortium/ITKSoftwareGuide/commit/81c741c))

#### Documentation Updates

- Correct signed long mangling and C++ variables ([1481a04](https://github.com/InsightSoftwareConsortium/ITKSoftwareGuide/commit/1481a04))

### Niels Dekker (2):

#### Enhancements

- Update compiler versions for C++14 ([80b8f89](https://github.com/InsightSoftwareConsortium/ITKSoftwareGuide/commit/80b8f89))
- Update Xcode Apple Clang compiler for nightly dashboard ([f65f786](https://github.com/InsightSoftwareConsortium/ITKSoftwareGuide/commit/f65f786))