captcha image in zend framework

I have the following code,but what I got is broken link ! I have installed GD library and the proper font ! but nothing work ,so how to I can use image captcha in zendframework without broken link ,what the wrong ?

$captcha = new Zend_Form_Element_Captcha('Captcha',arr开发者_如何学编程ay(
        'captcha' => array('captcha' => 'Image', 'wordLen' => 6, 
        'timeout' => 300, 'width' => 300, 'height' => 100, 
        'imgUrl' => '/captcha',
        'imgDir' => APPLICATION_PATH . '/../public/captcha', 
        'font' => APPLICATION_PATH . '/../public/fonts/LiberationSansRegular.ttf')));

//sorry

---

Try using:

'/public/captcha'

Instead of:

APPLICATION_PATH . '/../public/captcha'

--

What I did in my application was add a couple of lines in the main index.php file to have direct access to the public folder using a constant variable:

// Define path to public directory
defined('PUBLIC_PATH')
    || define('PUBLIC_PATH', realpath(dirname(__FILE__) . '/../public'));

Then just use:

PUBLIC_PATH . '/captcha'

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I found the problem.. It comes from : )

        if ( in_array( strtolower( ini_get( 'magic_quotes_gpc' ) ), array( '1', 'on' ) ) ) {
        $_POST = array_map( 'stripslashes', $_POST );
        $_GET = array_map( 'stripslashes', $_GET );
        $_COOKIE = array_map( 'stripslashes', $_COOKIE );
        }

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APPLICATION_PATH . '/../public/captcha' must exist and apache/php must have write access to it.