dede后台无法上传图片的解决办法

$imtypes = array("image/pjpeg","image/jpeg","image/gif","image/png","image/xpng","image/wbmp","image/bmp");
if(in_array(strtolower(trim($ {
    $_key.'_type'
}
)),$imtypes)) {
    $image_dd = @getimagesize($$_key);
    if (!is_array($image_dd)) {
        exit('Upload filetype not allow !');
    }
}