Lazarus - rotate Image

procedure TForm1.Button2Click(Sender: TObject);
var
  i,j: integer;
  noveI,noveJ: integer;
begin
  Image2.Canvas.FillRect(Image2.ClientRect);
  for i:=0 to Image1.Width-1 do
   for j:=0 to Image1.Height-1 do
    begin
    noveI:=Round((i)*cos(45)+(j)*sin(45));
    noveJ:=Round((j)*cos(45)-(j)*sin(45));
    Image2.Canvas.Pixels[i,j]:=Image1.Canvas.Pixels[novei,novej];
    end;
end;