function TileImage(const FileName: TFileName; Sender: TObject): Boolean;
 var
 x, y: Integer;
 Bmp: TBitmap;
 begin
 if FileExists(FileName) then
 begin
 bmp := TBitmap.Create;
 try
 bmp.LoadFromFile(FileName);
 with (Sender as TImage) do
 begin
 for x := 0 to (Width div bmp.Width) do
 for y := 0 to (Height div bmp.Height) do
 Canvas.Draw(x * bmp.Width, y * bmp.Height, bmp);
 end;
 finally
 bmp.Free;
 end;
 Result := True;
 end
 else
 Result := False;
 end;

 procedure TForm1.Button1Click(Sender: TObject);
 begin
 if Opendialog1.Execute then
 TileImage(OpenDialog1.FileName, Image1);
 end;