Would anyone know about the meaning of 3 parameters: "nIncrement" 、"init_amplitude"、" zdir_multiply_regul" in the algorithm "Vip Bias correction"?
Thank you very much!!
A Problem About "Vip Bias correction"
-
Jean-Francois Mangin
- Posts: 337
- Joined: Mon Mar 01, 2004 10:24 am
- Location: Neurospin, CEA, France
- Contact:
These parameters are related to the minimization algorithm. In general you can get a short description of the parameters of Vip library using the -h flag, And some more information in the related paper (which is not true in that case, a lot of improvements have been added latter on...)
nIncrement is related to the sampling used to upgrade one given value of the field. nIncrement=1 means one multiplicative value above 1., and one under 1.. If nIncrement is larger, more values are tried by the underlying Gibbs sampler.
init_amplitude defines the range in which the initial field values are randomly chosen.
zdir_multiply_regul is a way to lower the regularization in the Z direction, because some of the MR scan have a huge bias in Z. The provided value is multiplied with the global weight of regularization for the Z direction.
nIncrement is related to the sampling used to upgrade one given value of the field. nIncrement=1 means one multiplicative value above 1., and one under 1.. If nIncrement is larger, more values are tried by the underlying Gibbs sampler.
init_amplitude defines the range in which the initial field values are randomly chosen.
zdir_multiply_regul is a way to lower the regularization in the Z direction, because some of the MR scan have a huge bias in Z. The provided value is multiplied with the global weight of regularization for the Z direction.