Dear All,
I have a question about the SPM volume smoothing function. I noticed that the SPM smoothing function only sets the Gaussian kernel shape, but no entrance for setting the box size (namely how many voxels will be convolved) and instead use the default adapted size. As follows in spm_smooth.m,
s = s./VOX;
s1 = s/sqrt(8*log(2));
x = round(6*s1(1)); x = -x:x; x = spm_smoothkern(s(1),x,1); x = x/sum(x);
……
I am wondering what is the consideration for this setting (why the factor is 6 before the s1(1) ? ) ? The setting "x=-x:x" will result in a very large box size (although the elements near the bounder are zeros)
Thank you,
NZuo
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PhD, Brainnetome Center
National Laboratory of Pattern Recognition
Institute of Automation, Chinese Academy of Sciences
Beijing, China
Tel, +86 10 8254 4768
Fax, +86 10 8254 4777
http://www.brainnetome.org/
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