algorithms.fwhm¶
Module: algorithms.fwhm
¶
Inheritance diagram for nipy.algorithms.fwhm
:
This module provides classes and definitions for using full width at half maximum (FWHM) to be used in conjunction with Gaussian Random Field Theory to determine resolution elements (resels).
A resolution element (resel) is defined as a block of pixels of the same size as the FWHM of the smoothed image.
There are two methods implemented to estimate (3d, or volumewise) FWHM based on a 4d Image:
fastFHWM: used if the entire 4d Image is available iterFWHM: used when 4d Image is being filled in by slices of residuals
Classes¶
ReselImage
¶

class
nipy.algorithms.fwhm.
ReselImage
(resels=None, fwhm=None, **keywords)¶ Bases:
nipy.algorithms.fwhm.Resels

__init__
(resels=None, fwhm=None, **keywords)¶ Initialize resel image
Parameters: resels : core.api.Image
Image of resel per voxel values.
fwhm : core.api.Image
Image of FWHM values.
keywords :
dict
Passed as keywords arguments to core.api.Image

Resels
¶

class
nipy.algorithms.fwhm.
Resels
(coordmap, normalized=False, fwhm=None, resels=None, mask=None, clobber=False, D=3)¶ Bases:
nipy.externals.six.Iterator
The Resels class.

__init__
(coordmap, normalized=False, fwhm=None, resels=None, mask=None, clobber=False, D=3)¶ Initialize resels class
Parameters: coordmap :
CoordinateMap
CoordinateMap over which fwhm and resels are to be estimated. Used in fwhm/resel conversion.
fwhm :
Image
Optional Image of FWHM. Used to convert FWHM Image to resels if FWHM is not being estimated.
resels :
Image
Optional Image of resels. Used to compute resels within a mask, for instance, if FWHM has already been estimated.
mask :
Image
Mask over which to integrate resels.
clobber :
bool
Clobber output FWHM and resel images?
D :
int
Can be 2 or 3, the dimension of the final volume.

fwhm2resel
(fwhm)¶ Convert FWHM fwhm to equivalent reseels per voxel
Parameters: fwhm : float
Convert an FWHM value to an equivalent resels per voxel based on step sizes in self.coordmap.
Returns: resels : float

integrate
(mask=None)¶ Integrate resels within mask (or use self.mask)
Parameters: mask :
Image
Optional mask over which to integrate (add) resels.
Returns: total_resels :
the resels contained in the mask
FWHM : float
an estimate of FWHM based on the average resel per voxel
nvoxel: int
the number of voxels in the mask

resel2fwhm
(resels)¶ Convert resels as resels to isotropic FWHM
Parameters: resels : float
Convert a resel value to an equivalent isotropic FWHM based on step sizes in self.coordmap.
Returns: fwhm : float
