(a) A slice of an MR volume obtained from a GE 4T scanner,15
(b) segmentation of the volume into 3 classes—cerebral-spinal fluid (CSF), gray matter (GM) and white matter (WM)—by Fuzzy C means (FCM),16
(c) estimated gain field using a non-parametric non-uniform intensity normalization (N3)12 method, (d) the corresponding inhomogeneity corrected image, (e) FCM16 segmentation of the N3 corrected image. The corrected image is a better representation of the tissues, where the intensities are more homogeneoous. This is reflected in the segmentation improvement in (e) from the gross error in (b).