[ITK] Valid FFT Sizes

[Wood, Tobias]

Hello,

I am trying to FFT a moderately large 3D image but am receiving a contradictory error message:

itk::ERROR: VnlForwardFFTImageFilter(0x3038500): Cannot compute FFT of image with size [416, 416, 60]. VnlForwardFFTImageFilter operates only on images whose size in each dimension is a multiple of 2, 3, or 5.

All the image dimensions are a multiple of 2!  Are the dimensions restricted to be powers of 2/3/5 instead of multiples?

I can pad the image out to a sensible size (e.g. 512x512x64), but would like to know if there are any other restrictions I should be aware of before going around in circles? 

Thanks,
Toby