procedure TformMain.Button1Click(Sender: TObject);
var
  i: Integer;
  Bitmap: TBitmap;
begin
  if OpenDialog.Execute then
    begin
      Pdf.FileName := OpenDialog.FileName;
      Pdf.Active := True;
      try
        for i := 1 to Pdf.PageCount do
          begin
            Pdf.PageNumber := i;
            Bitmap := Pdf.RenderPage(0,0,Round(Pdf.PageWidth),Round(Pdf.PageHeight));
            try
              Batch.AppendImage(Bitmap);
            finally
              FreeAndNil(Bitmap);
            end;
          end;
      finally
        Pdf.PageNumber := 1;
        Pdf.Active := False;
      end;
   end;
end;