I am using nilearn and nipy package for python processing FMRI data. When computing mask, it says:
Compute and write the mask of an image based on the grey level This is based on an heuristic proposed by T.Nichols: find the least dense point of the histogram, between fractions m and M of the total image histogram.
and
This is based on an heuristic proposed by T.Nichols: find the least dense point of the histogram, between fractions lower_cutoff and upper_cutoff of the total image histogram.
In both masking functions of nilearn and nipy. Who is T.Nichols? I wasn't able to google him/her out.
here are the links to the functions:
http://nipy.org/nipy/stable/api/generated/nipy.labs.mask.html
https://nilearn.github.io/building_blocks/generated/nilearn.masking.compute_epi_mask.html