warpinit: don't use Image::row() method on non-direct-IO images
warpinit: don't use Image::row() method on non-direct-IO images

MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3