Delphi 图片jpg格式转换成bmp格式 保存到数据库

procedure TfrmPatientConfirm.btn1Click(Sender: TObject);
var
  jpg :TJPEGImage;
  bmp :TBitmap;
begin
  //jpg转换成bmp
  jpg := TJPEGImage.Create;
  bmp := TBitMap.Create;
  try
    jpg.LoadFromFile('sign.jpg');
    bmp.Assign(jpg);
    bmp.SaveToFile('sign_data.bmp');
  finally
    bmp.FreeImage;
    bmp.Free;
    jpg.Free;
  end;

  //bmp保存到数据库(字段类型为image)
  with cdsPatientConfirm do
  begin
    Append;
    TBlobField(FieldByName('sign_data')).
      LoadFromFile(ExtractFiledir(Application.exeName)+'\sign_data.bmp');
    Post;

    if ApplyUpdates(0) <> 0 then
    begin
      ShowMessage('签名数据保存失败！');
      Exit;
    end;
  end;
end;