Hi Viktor

it is a 3D erosion, and a cubic 3x3x3 structuring element.

cheers Bruce On Tue, 19 Feb 2019, Viktor Domazetoski wrote:

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Dear FreeSurfer experts,

I would like to enquire about the command mri_extract_label. More specifically I am looking for information about the -erode argument. Therefore I have a few questions:

1. Is a 3D erosion of the entire brain or a 2D slice by slice erosion used?
2. What structuring element (regarding the shape and size of the kernel) is used for the erosion for a given argument value (e.g. for the command mri_extract_label -erode 1)?

Thank you in advance! Kind regards, Viktor