code: def getData(self,exten=None):
          
          if exten.lower().find('sci') > -1:
              # For SCI extensions, the current file will have the data
              fname = self._filename
          else:
              # otherwise, the data being requested may need to come from a
              # separate file, as is the case with WFPC2 DQ data.
              #
              # convert exten to 'sci',extver to get the DQ info for that chip
              extn = exten.split(',')
              sci_chip = self._image[self.scienceExt,int(extn[1])]
              fname = sci_chip.dqfile
  
          extnum = self._interpretExten(exten)
          if self._image[extnum].data is None:
              if os.path.exists(fname):
                  _image=fileutil.openImage(fname, clobber=False, memmap=False)
                  _data=fileutil.getExtn(_image, extn=exten).data
                  _image.close()
                  del _image
                  self._image[extnum].data = _data
              else:
                  _data = None
          else:
              _data = self._image[extnum].data
  
          return _data
docs: Return just the data array from the specified extension
              fileutil is used instead of fits to account for non-
              FITS input images. openImage returns a fits object.