Hi,
I’m trying to create a ROI by convolving 2 binary masks of the same matrix dimensions using SPM ImCalc.
However, when I use the operation i1.*i2, it gives me a different answer to what I get when multiplying the matrices using .* in a matlab script
e.g. in one case
image 1 = 143 voxels
image 2 = 1714 voxels
in SPM ImCalc:
image3= image 1 .* image 2 = 153 voxels
in Matlab script
image3= image 1 .* image 2 = 18 voxels
Is ImCalc doing something different with .* than I expect with Matlab? It should be impossible for image 3 to have more voxels than one of the initial images, and I’d expect SPM and Matlab’s output to agree
Any ideas welcome.
thanks,
Susan
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