/**
* Generate a new Captcha.
* The phrase contained in the Captcha is automatically placed
* in the user's session for later verification.
*
* @param $width int The width of the generated captcha image.
* @param $height int The height of the generated captcha image.
* @return Captcha object for further options and output.
*/
public static function generate($width = 150, $height = 40)
{
$ret = new Captcha();
$ret->build($width, $height);
Session::set("CAPTCHA_VALUE", $ret->getPhrase());
return $ret;
}
