Apologize for the basic question :

I am trying to coregister a 4D.nii file to its related structural scan.

By using the "Coreg - estimate and reslice option", the ref image is the structiral scan and the source image is the first (aligned) frame while the Other images are the remaining 443 frames.

The reslice option generates a 5 GB ra image (for 1 subjectg).

Is there a way not to generate such an enormous file ?

Many thanks for your replies,

Gabriel