Hi,
Thank you so much for your reply. Actually, I created some masks as my ROI. And I give the masks different values. Then I use 3dcalc to compose these masks.like:3dcalc -a AN.nii -b VN.nii -c DMN.nii -d ECN.nii -expr 'a+b+c+d' -prefix Network.nii. The final result is the first picture.
Now what I want to do is add the edges for the mask. Then I will use SUMA to get a surface. So I want to add the edges to make the boundary between ROI clearer, like the second picture.