code: def subimage(self, blc=(), trc=(), inc=(), dropdegenerate=True):
          
          return image(self._subimage(self._adjustBlc(blc),
                                      self._adjustTrc(trc),
                                      self._adjustInc(inc),
                                      dropdegenerate))
docs: Form a subimage.
  
          An image object containing a subset of an image is returned.
          The arguments blc (bottom left corner), trc (top right corner),
          and inc (stride) define the subset. Not all axes need to be specified.
          Missing values default to begin, end, and 1.
  
          By default axes with length 1 are left out.
  
          A subimage is a so-called virtual image. It is not stored, but only
          references the original image. It can be made persistent using the
          :func:`saveas` method.