Downsampling an image using FSL using FSL

Question

I have a set of fMRI images. One group has a dimension of 90 x 60 x 12 x 350 with a voxel size of 1 x 1 x 1 mm (350 volumes). The other group has a dimension of 80 x 35 x 12 x 350 with a voxel size of 0.2 x 0.2 x 0.5 mm. I use one of the images as a reference image for registration. Due to the difference in resolution, registration fails (with flirtation). Therefore, I must first reduce or increase. I tried the following approach:

flirt -in input_image \ -ref good_size_image \ -out output_image \ -applyxfm \ -init / usr / share / fsl / 5.0 / etc / flirtsch / ident.mat

This does not work, not for downsampling, not for upsampling.

How do I do the right sampling / upsampling?

Answer 1

If I understand correctly, do you have images with a spatial length of (a)9 x 6 x 1.2 cm ^ 3 and (b)1.6 x 0.7 x 0.6 cm ^ 3? They are quite small and very different. I can imagine that if image 2 covers a very specific subarea of ​​image 1 (because it is much smaller), you may need a good starting score to get the right result.

if input_imageit measures (b)and good_size_imagemeasures (a), and then with a call

flirt -in input_image 
      -ref good_size_image 
      -out output_image 
      -applyxfm 

( initoption in this case is not absolutely necessary),

, . , ( ), . (a) (b) , . .

applyisoxfm, .

flirt -in small_image -ref small_image -out small_1mm -applyisoxfm 1

, (b) 1x1x1 ^ 3. , , , . , 0,5 , ?

FSL  , .

Answer 2

fslmaths -subsamp2?