base64编码解码图片有关问题

       $aaaa=base64_encode(file_get_contents('http://t10.baidu.com/it/u=3419096712,54017040&fm=55&s=6A00F50B4AEB0298352025A50300A022&w=121&h=81&img.JPEG'));
        file_put_contents('./Uploads/jquery.jpg', file_get_contents(base64_decode($aaaa)));

$aaaa=file_get_contents('http://img211.poco.cn/mypoco/myphoto/20080924/3526959720080924225448061_640.jpg');
file_put_contents('./Uploads/jquery.jpg', $aaaa);