Hello Nancy,It is generally better to always register with the higher-resolution image as a reference, the resulting transformation can then be inverted and used to transform the structural image to low-resolution space.Kind RegardsMatthewOn 14 Mar 2017, at 13:14, Nancy Li <[log in to unmask]> wrote:Hi experts,Good morning. Now I want to change the resolution of 3D structure image to a low resolution image. How to run in FSL. Or may be thre some way in Matlab? I tried flirt command , but it failed to flirt 3D high resolution image to low reslution function image. Thereis some problem in it. How to resolve. I am eager to get your help. Thank you soso much!BestNancy