请问:为什么我的图片显示不出来呢
//==============================
<?php
session_start();
$table = array('pic0'=>'猫','pic1'=>'狗','pic2'=>'蛇','pic3'=>'马');
$index = rand(0,3);
$value = $table['pic'.$index];
$_SESSION['authcode']=$value;
$filename=dirname(__FILE__).'\\pic'.$index.'.jpg';
$contents = file_get_contents($filename);
header('content-type:image/jpg');
echo $contents;