@@ -710,6 +710,10 @@ def set_zooms(self, zooms):
 pixdims = hdr['pixdim']
 pixdims[1:ndim + 1] = zooms[:]
 
+def get_norm_zooms(self):
+''' Get zooms in mm/s units '''
+return self.get_zooms()
+
 def as_analyze_map(self):
 """ Return header as mapping for conversion to Analyze types
 

@@ -1626,6 +1626,38 @@ def set_xyzt_units(self, xyz=None, t=None):
 t_code = unit_codes[t]
 self.structarr['xyzt_units'] = xyz_code + t_code
 
+def get_norm_zooms(self, raise_unknown=False):
+raw_zooms = self.get_zooms()
+xyz_zooms = raw_zooms[:3]
+t_zoom = raw_zooms[3] if len(raw_zooms) > 3 else None
+
+xyz_code, t_code = self.get_xyzt_units()
+xyz_msg = t_msg = ''
+if xyz_code == 'unknown':
+xyz_msg = 'Unknown spatial units'
+xyz_code = 'mm'
+if t_code == 'unknown' and t_zoom is not None:
+t_msg = 'Unknown time units'
+t_code = 'sec'
+if raise_unknown and (xyz_msg, t_msg) != ('', ''):
+if xyz_msg and t_msg:
+msg = 'Unknown spatial and time units'
+else:
+msg = xyz_msg or t_msg
+raise ValueError("Error: {}".format(msg))
+if xyz_msg:
+warnings.warn('{} - assuming mm'.format(xyz_msg))
+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_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
+
 def _clean_after_mapping(self):
 ''' Set format-specific stuff after converting header from mapping