Spatial Gradient Calculation

The spatial_gradient function calculates the spatial gradient of a NeuroVol instance within the specified mask.

Usage

spatial_gradient(vol, mask, sigma = 0.5)

Arguments

vol

A NeuroVol instance for which the spatial gradient should be calculated.

mask

A NeuroVol mask defining the voxels to include in the spatial gradient calculation. If the mask contains numeric data, nonzero values will define the included voxels. If the mask is a LogicalNeuroVol, then TRUE will define the set of included voxels.

sigma

A numeric value controlling the spatial weighting function. Default is 0.5.

Value

A NeuroVol instance containing the spatial gradient values for the input vol.

See also

spatial_laplacian, weighted_spatial_adjacency

Examples

if (FALSE) { # \dontrun{
mask <- neuroim2::NeuroVol(array(1, c(20,20,20)), neuroim2::NeuroSpace(c(20,20,20)))
input_vol <- neuroim2::NeuroVol(array(runif(20*20*20), c(20,20,20)),
  neuroim2::NeuroSpace(c(20,20,20)))
gradient_vol <- spatial_gradient(input_vol, mask)
} # }