[ITK] N4BiasFieldCorrectionImageFilter units for FWHM?

[Wood, Tobias]

Hello,

What are the units for SetBiasFieldFullWidthAtHalfMaximum() method on N4BiasFieldCorrectionImageFilter? mm? Voxels? Something else entirely?

I am trying to bias-correct some pre-clinical images that have small voxels (100 micron isotropic), and reducing the FWHM by a factor of 10 makes quite a difference to the output bias field.

Best wishes,
Toby