多次刷新验证码，可能出现500错误

[haha357]

wordpress-theme-puock/inc/php-captcha.php

Line 309 in 3e62a99

$red = abs(min(255,$red - $increase));

多次刷新验证码，可能出现500错误，原因是$red, $green, $blue三个参数可能超出255。
可按以下修改解决。
$red = abs(min(255,abs($red - $increase)));
$green = abs(min(255,abs($green - $increase)));
$blue = abs(min(255,abs($blue - $increase)));