验证码，因其本身有错无法显示

修改 image.class.php

static function output($im, $type='png', $filename='') {
/*添加*/
ob_clean();

header("Content-type: image/" . $type);
$ImageFun = 'image' . $type;
if (empty($filename)) {
$ImageFun($im);
} else {
$ImageFun($im, $filename);
}
imagedestroy($im);
}