PHP生成验证码第二弹，强势来袭

function getVerify()
{

    session_start();
    ob_clean ();   //清除缓冲区    
    header("Content-type:image/png");

    $img_width=40;
    $img_height=20;

    srand(microtime()*100000);
    for($i=0;$i<4;$i++)
    {
        $new_number.=dechex(rand(0,15));
    }

    $_SESSION[check_auth]=$new_number;
    $new_number=imageCreate($img_width,$img_height);//创建图象
    ImageColorAllocate($new_number,255,255,255);  //设置背景色为白色

    for($i=0;$i    {
        $font=mt_rand(3,5);
        $x=mt_rand(1,1) + $img_width*$i/4;
        $y=mt_rand(1,$img_height/4);
        $color=imageColorAllocate($new_number,mt_rand(0,100),mt_rand(0,150),mt_rand(0,200));//设置字符颜色
        imageString($new_number,$font,$x,$y,$_SESSION[check_auth][$i],$color);//