Tom Birdsong

@dzenanz If you have time could you please verify whether you can reproduce? I haven't seen an upgrade path issue for ITK like this before. Simple enough to re-install, but...

@thewtex Ping for visibility

I don't see any commit messages in ITKImageGrid since 5.3rc02 was tagged on Oct 27th that should changed Python module behavior 🤔 [ITKImageGrid history](https://github.com/InsightSoftwareConsortium/ITK/commits/master/Modules/Filtering/ImageGrid) [tag history](https://github.com/InsightSoftwareConsortium/ITK/tags)

Observed a different error loading ITKFFT this morning that was resolved again by re-installing ITK packages. Haven't tried recreating with an upgrade path. ``` >>> import itk >>> itk.__version__ '5.3.0'...

Currently seeing a similar issue again with `ITKImageSources` in my local environment for v5.3rc04: ```py >>> import itk >>> itk.auto_progress(2) >>> itk.DisplacementFieldTransform Loading ITKPyBase... done Traceback (most recent call last):...

@jcfr @thewtex Could one of you please comment on the severity of this bug in regards to the v5.3 roadmap? I have not been able to allocate time to investigating...

@dzenanz Any thoughts on this one? I do not see any recent changes in `itk::StatisticsUniqueLabelMap` files.

Strange, but good that it is passing now. I will leave this open as a data point in the event that it happens again.

Related to speedup with [https://github.com/InsightSoftwareConsortium/ITKVkFFTBackend](https://github.com/InsightSoftwareConsortium/ITKVkFFTBackend)

Investigation shows that underlying FFT classes also request the largest possible region in each FFT direction, which limits our ability to optimize for image subregions. Exploring the impact of propagating...