Hi Can you please help me to recover RAS voxel coordinates (I need to use them in the label file) from the talairach ones. I think that the transformation I should use is the one in Talairach.xfm (T), but If I copy one vertex coordinates P (MNI Tal) from tksurfer, apply the transformation: I don't have the coordinate of the same RAS vertex. Ps:I tried to add 0 0 0 1 to the transform to make it 4x4, and 1 to the point to make it 4x1 Please correct me if the transformation and the displayed values in Tksurfer are not related to the Subject transformation in Talaraich space. Thanks a lot Leila