var
  MyPolySelArray: array of TPoint;
  I: Integer;
begin
  // Create an array of TPoints of the polygon selection in a TImageEnView
  SetLength( MyPolySelArray, ImageEnView1.PolySelCount );
  for I := 0 to ImageEnView1.PolySelCount - 1 do
    MyPolySelArray[ I ] := ImageEnView1.PolySel[ I ];
end;

// Create a polygon selection from an array of TPoints
for I := Low( MyPolySelArray ) to High( MyPolySelArray ) do
  ImageEnView1.AddSelPoint( MyPolySelArray[ I ].x, MyPolySelArray[ I ].y );
ImageEnView1.EndSelect();