def METHOD_NAME(self, intersection):
    '''Take an intersection in mm in the abstract coordinate frame
    attached to the sensor and convert it to coordinates in units of
    pixels in image space. This basic implementation assumes that the
    two origins coincide, the fast axis is aligned along dir1 and
    the slow axis along dir2. This does no bounds checking, it is
    purely a units conversion function'''
    fast = intersection[0] / self._px_size_fast
    slow = intersection[1] / self._px_size_slow
    return (fast, slow)