procedure TForm1.RotateFrame(Index: Integer; Angle: double);
var
  fn: string;
begin
  fn := GetBackupFolder() + ImageEnMView1.MIO.Params[Index].Filename + '_' + IntToStr( Index ) + '.png';
  ImageEnMView1.GetImageToFile( Index, fn );
  ImageEnMView1.IEMBitmap.Rotate( Index, Angle, ierBicubic );
end;

function TForm1.CanUndo(Index: Integer): Boolean;
var
  fn: string;
begin
  fn := GetBackupFolder() + ImageEnMView1.MIO.Params[Index].Filename + '_' + IntToStr( Index ) + '.png';
  Result := FileExists( fn );
end;

procedure TForm1.UndoFrame(Index: Integer);
var
  fn: string;
begin
  fn := GetBackupFolder() + ImageEnMView1.MIO.Params[Index].Filename + '_' + IntToStr( Index ) + '.png';
  ImageEnMView1.SetImageFromFile( Index, fn );
  DeleteFile( fn );
end;