imagestats

Functions for computing image statistics

count_nonzero_voxels(img)

Count number of non-zero voxels

mask_volume(img)

Compute volume of mask image.

count_nonzero_voxels

nibabel.imagestats.count_nonzero_voxels(img)

Count number of non-zero voxels

Parameters
imgSpatialImage

All voxels of the mask should be of value 1, background should have value 0.

Returns
countint

Number of non-zero voxels

mask_volume

nibabel.imagestats.mask_volume(img)

Compute volume of mask image.

Equivalent to “fslstats /path/file.nii -V”

Parameters
imgSpatialImage

All voxels of the mask should be of value 1, background should have value 0.

Returns
volumefloat

Volume of mask expressed in mm3.

Examples

>>> import numpy as np
>>> import nibabel as nb
>>> mask_data = np.zeros((20, 20, 20), dtype='u1')
>>> mask_data[5:15, 5:15, 5:15] = 1
>>> nb.imagestats.mask_volume(nb.Nifti1Image(mask_data, np.eye(4)))
1000.0