cur如何显示验证码

cur怎么显示验证码
要显示的网址为:https://pin.aliyun.com/get_img?sessionid=47b7c5dbac3eb7cf9f678227fadd3e67&identity=taobao.login&type=150_40&_r_=1427727728245

用了一些常规方法代码都不行呢，是不是有些有些参数没有传入呢？有朋友知道的指点下小弟哈

$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, 'https://pin.aliyun.com/get_img?sessionid=47b7c5dbac3eb7cf9f678227fadd3e67&identity=taobao.login&type=150_40&_r_=1427727728245'); 
curl_setopt($curl, CURLOPT_REFERER, '');
curl_setopt($curl, CURLOPT_USERAGENT, '');
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1); 
$result = curl_exec($curl);
header('Content-type: image/JPEG');
echo $result;

------解决思路----------------------

$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, 'https://pin.aliyun.com/get_img?sessionid=47b7c5dbac3eb7cf9f678227fadd3e67&identity=taobao.login&type=150_40&_r_=1427727728245'); 
curl_setopt($curl, CURLOPT_REFERER, ''); //这句可以不要
curl_setopt($curl, CURLOPT_USERAGENT, ''); //这句可以不要
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1); 
curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, FALSE); //这句一定要，因为是 https
curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, FALSE); //这句可以不要
$result = curl_exec($curl);
header('Content-type: image/JPEG'); //这句可以不要
echo $result;