C:	a given scene corrupted by background variation (such as the one produced by an imaging device).
Cbt = (C, fbt):	a scene representing the true background variation component in C.
Cu = (C, fu):	C without the background variation component Cbt.
Cc = (C, fc):	the scene resulting from applying a correction algorithm α to C to suppress background variation in C.
Cbe = (C, fbe):	a scene representing the background variation component in C estimated by a correction algorithm α.
|C|:	the number of voxels in C.
SPR	the set of all scenes acquired as per a given MRI protocol P and for a given body region R.