FIX: Various unit issues

Author: effigies

nibabel/nifti1.py

@@ -1630,8 +1630,6 @@ def set_xyzt_units(self, xyz=None, t=None):
             xyz = 0
         if t is None:
             t = 0
-        xyz_code = self.structarr['xyzt_units'] % 8
-        t_code = self.structarr['xyzt_units'] - xyz_code
         xyz_code = unit_codes[xyz]
         t_code = unit_codes[t]
         self.structarr['xyzt_units'] = xyz_code + t_code
@@ -1661,11 +1659,11 @@ def get_norm_zooms(self, raise_unknown=False):
         if t_msg:
             warnings.warn('{} - assuming sec'.format(t_msg))
 
-        xyz_factor = {'meter': 0.001, 'mm': 1, 'usec': 1000}[xyz_code]
-        t_factor = {'sec': 1, 'msec': 1000, 'usec': 1000000}[t_code]
+        xyz_factor = {'meter': 1000, 'mm': 1, 'micron': 0.001}[xyz_code]
+        t_factor = {'sec': 1, 'msec': 0.001, 'usec': 0.000001}[t_code]
 
-        xyz_zooms = tuple(np.array(xyz_zooms) / xyz_factor)
-        t_zoom = (t_zoom / t_factor,) if t_zoom is not None else ()
+        xyz_zooms = tuple(np.array(xyz_zooms) * xyz_factor)
+        t_zoom = (t_zoom * t_factor,) if t_zoom is not None else ()
 
         return xyz_zooms + t_zoom