View file captcha.php

<?PHP

define('H', $_SERVER['DOCUMENT_ROOT'] . '/');

session_name('SESS');
session_start();

require H.'sys/inc/captcha.php';

$_SESSION['captcha'] = '';

for ($i = 0; $i < 5; $i++) {
	$_SESSION['captcha'].=mt_rand(0, 9);
}

$captcha = new captcha($_SESSION['captcha']);
$captcha->create();
$captcha->colorize();
$captcha->output();