Igor Yakushev wrote:
> i'd like to perform a simple operation: to divide one image by another one
> (FDG-PET). I used "ImCalc" and got a white space with NaN intensity
Dear Igor,
The white space -- is that visible in SPM's Check Registration? My
guess is that you're viewing the images in fslview, which get min/max
intensity values to scale the images, and hence doesn't really like
NaNs being present. If you are using fslview, you can manually enter
limits for the intensity ranges and then you should see the image you
want. And/or you can use avwmaths to set the NaNs to zero, with:
avwmaths your_image -nan image_unNaNed
However, with regard to further processing in SPM, at least in spm5
these NaN values will be ignored if you have implicit masking set,
which is probably what you want.
If I've misunderstood what you want, investigate the Matlab function
isnan in relation to ImCalc and you should be able to get pretty much
whatever outcome you want.
Hope this helps,
Ged.
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