% create gaussian kernel with size 2 (in voxels!)
% values in the kernel smaller than 1e-4 are discarded
% as they don't play any big role for the sum of weights
k = smoothkern(2, 1e-4);

% a VTC is loaded (datatype: uint16)
vtc = xff('*.vtc');

% the data is smoothed in dims 2 through 4 -> store as single!
vtc.VTCData = single(flexinterpn(vtc.VTCData, ...
    [Inf, Inf, Inf, Inf; ones(2, 4); size(vtc.VTCData)], ...
    {[0; 1; 0], k, k, k}, {1, 1, 1, 1}, 0));

% some patches necessary
vtc.FileVersion = 3;
vtc.DataType = 2;