[MINC-users] multiply with 0 not equal to 0?

[Mishkin Derakhshan]

Hi,

I have a binary mask that I multiply with a volume and I am expecting
that in the resultant image, everywhere that the mask was 0, the
resulting image should be zero as well. Instead, it is some number
close to zero but not necessarily 0.

I am not sure if this is a problem with how register/display display
the values or with the data itself.

I used this command
mincmath -mult mask.mnc volume.mnc out.mnc

(minccalc -expression "A[0]*A[1]" mask.mnc volume.mnc out.mnc doesn't
seem to work either).

The mask is a unisgned byte, real range 0 to 1, voxel range 0 to 255.
The volume is a signed short. real range -91.323 to 1364.351, voxel
range 0 to 4095.

I have tried changing the order of the multiplication, adding -double,
-short, -int, -long, -byte, -unsigned, -signed to the mincmath command
but nothing seems to work.

The data can be found here if you want to see for yourself.
http://www.bic.mni.mcgill.ca/users/mishkin/files/

thanks,
mishkin