I'm trying to produce an image volume containing noise, with a given spatial smoothness. I tried this:
3dcalc -a 'filtered_func_data.nii.gz[0]' -expr 'a*0+gran(0,1)' -prefix noise.nii.gz
which gives me noise as expected, then:
3dBlurToFWHM -input noise.nii.gz -blurmaster noise.nii.gz -prefix smoothnoise.nii.gz -FWHM 5
This program fails to converge. The estimated smoothness peaks and then starts declining. The output shows regions of smoothness and others equal to the input.
What am I doing wrong?
