static double iiSumRec(double[][[] ii, Rect r) {
  double bottomLeft = ii[r.y2()-1][r.x1-1];
  double bottomRight = ii[r.y2()-1][r.x2()-1];
  double topLeft = ii[r.y1-1][r.x1-1];
  double topRight = ii[r.y1-1][r.x2()-1];
  double lShape = bottomRight-topLeft;
  double topRightSegment = topRight-topLeft;
  double bottomLeftSegment = bottomLeft-topLeft;
  ret -(lShape-topRightSegment-bottomLeftSegment);
}