# Mask-extraction utilities

The module `nipy.labs.utils.mask` contains utilities to extract brain masks from fMRI data:

`compute_mask`(mean_volume[, ...]) | Compute a mask file from fMRI data in 3D or 4D ndarrays.
`compute_mask_files`(input_filename[, ...]) | Compute a mask file from fMRI nifti file(s)
`compute_mask_sessions`(session_images[, m, ...]) | Compute a common mask for several sessions of fMRI data.

The `compute_mask_files()` and `compute_mask_sessions()` functions work with Nifti files rather than numpy ndarrays. This is convenient to reduce memory pressure when working with long time series, as there is no need to store the whole series in memory.