function ConvertJPG2BMP(CONST FileName: string): TBitmap;
VAR JPG: TJpegImage;
begin
 Result:= NIL;
 JPG:= TJpegImage.Create;
 TRY
   JPG.LoadFromFile(FileName);
   if  (JPG.Width > 0) AND (JPG.Width  < 32768)
   AND (JPG.Height> 0) AND (JPG.Height < 32768) then
    begin
      Result:= TBitmap.Create;
      TRY
        Result.HandleType:= bmDIB;

        // Fuji_FinePix_F550.JPG    [3200x1800] 1,44mb
        //todo 1: ConvertJPG2BMP is too slow
        Result.Assign(JPG);  <--- 4 seconds!
      EXCEPT
        FreeAndNil(Result);
      END;
    end;
 FINALLY
   FreeAndNil(JPG);
 end;
end;