Table 2.

notational description.

Symbols	Description	Symbols	Description
$I_0$	Fixed image	$I_1$	Moving image
${\Omega }_0$	Fixed image field	${\Omega }_1$	Moving image field
$F_0^{SE}$	Fixed image multi-scale SE descriptors	$F_1^{SE}$	Moving image multi-scale SE descriptors
$d$	Deformation field	$D$	A set of deformation fields
$\overline{d}$	Mean deformation field	$C$	Cooccurrence matrix
m	Number of SE descriptors	$\delta$	Weighting parameter of SDM
s	Number of dimensions	$q$	Discretization degrees
n	Number of prior known deformation fields	$r$	Number of selected PCA components
$𝒩$	Normal distribution of SDM	$u$	Eigenvectors
$U$	Eigenvector matrix	$\tilde{U}$	Eigenvector matrix with selected eigenvectors
$\Sigma$	Diagonal matrix of eigenvalues	$\lambda$	Eigenvalues