SpatialSmoothingFD2D Method


Description

Spatially filters each recorded image in the STC files of an FMR project in the frequency domain.

Syntax

objDocument.SpatialSmoothingFD2D(intHighPass, intLowPass)

Remarks

Valid only if objDocument is of type FMR. The high- and low pass values are interpreted in cycles per spatial dimension measured in voxels (i.e. matrix size). In the rare case of a non-square matrices, the largest dimension is chosen as reference. A low pass value equal to or greater than half of the dimension (i.e. > 32 in the case of a 64 x 64 matrix) lets everyghing pass, it will have no effect (Nyquist theorem). In the GUI version (2D Data Preprocessing dialog), BrainVoyager sets the default value of the low pass filter to half of this value (i.e. 16 in case of a 64 x 64 matrix, 32 in case of a 128 x 128 matrix) which produces a modest spatial smoothing roughly equal to spatial smoothing with a FWHM of 4mm in the spatial domain. In the GUI version, the low-pass filter is turned off completely for 64 x 64 matrices and is only turned on by greater matrices. The high-pass filter is also turned off in the GUI version since such a spatial filter is not useful in the context of fMRI data analysis. To turn the high-pass filter off, specify "1" as the intHighPass argument.
The resulting filtered data is automatically saved to disk. The names for the new FMR project and the new STC prefix is determined as in the GUI version, i.e., if the FMR project "cg_objects.fmr" is used, the resulting new file on disk will be "cg_objects_pp.fmr". In addition, a set of new STC files, actuallly containing the smoothed data, is stored to disk. If, for example, the prefix in the source FMR project was "slice-" (referencing file slice-1.stc, slice-2.stc etc.), the STC prefix of the new FMR file will be "slice_pp-". If you do not want to use this implicit naming scheme, you might want to use the method SpatialSmoothingFD2DEx which allows to specify the name of the resulting FMR project and STC prefix.

Example

' VBScript
Set doc = BrainVoyager.
OpenDocument("cg_objects.fmr")
doc.
SpatialSmoothingFD2D 1, 32

// JScript
doc = BrainVoyager.
OpenDocument("cg_objects.fmr");
doc.
SpatialSmoothingFD2D(1, 32);

# PerlScript
$doc = $BrainVoyager->
OpenDocument("cg_objects.fmr");
$doc->
SpatialSmoothingFD2D(1, 32);