Изменить цвет текста и фона в образе reCaptcha

Question

Я использую класс reCaptcha (тот, который включен в библиотеку аутентификации Tank Auth для Codeigniter) и хотел узнать, можно ли изменить цвет фона и текста изображения reCaptcha возвращает ?

Вот фактический ReCaptcha Helper PHP код включен с Tank Auth:

<?php 
/* 
* This is a PHP library that handles calling reCAPTCHA. 
* - Documentation and latest version 
*   http://recaptcha.net/plugins/php/ 
* - Get a reCAPTCHA API Key 
*   http://recaptcha.net/api/getkey 
* - Discussion group 
*   http://groups.google.com/group/recaptcha 
* 
* Copyright (c) 2007 reCAPTCHA -- http://recaptcha.net 
* AUTHORS: 
* Mike Crawford 
* Ben Maurer 
* 
* Permission is hereby granted, free of charge, to any person obtaining a copy 
* of this software and associated documentation files (the "Software"), to deal 
* in the Software without restriction, including without limitation the rights 
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
* copies of the Software, and to permit persons to whom the Software is 
* furnished to do so, subject to the following conditions: 
* 
* The above copyright notice and this permission notice shall be included in 
* all copies or substantial portions of the Software. 
* 
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 
* THE SOFTWARE. 
*/ 

/** 
* The reCAPTCHA server URL's 
*/ 
define("RECAPTCHA_API_SERVER", "http://api.recaptcha.net"); 
define("RECAPTCHA_API_SECURE_SERVER", "https://api-secure.recaptcha.net"); 
define("RECAPTCHA_VERIFY_SERVER", "api-verify.recaptcha.net"); 

/** 
* Encodes the given data into a query string format 
* @param $data - array of string elements to be encoded 
* @return string - encoded request 
*/ 
function _recaptcha_qsencode ($data) { 
     $req = ""; 
     foreach ($data as $key => $value) 
       $req .= $key . '=' . urlencode(stripslashes($value)) . '&'; 

     // Cut the last '&' 
     $req=substr($req,0,strlen($req)-1); 
     return $req; 
} 



/** 
* Submits an HTTP POST to a reCAPTCHA server 
* @param string $host 
* @param string $path 
* @param array $data 
* @param int port 
* @return array response 
*/ 
function _recaptcha_http_post($host, $path, $data, $port = 80) { 

     $req = _recaptcha_qsencode ($data); 

     $http_request = "POST $path HTTP/1.0\r\n"; 
     $http_request .= "Host: $host\r\n"; 
     $http_request .= "Content-Type: application/x-www-form-urlencoded;\r\n"; 
     $http_request .= "Content-Length: " . strlen($req) . "\r\n"; 
     $http_request .= "User-Agent: reCAPTCHA/PHP\r\n"; 
     $http_request .= "\r\n"; 
     $http_request .= $req; 

     $response = ''; 
     if(false == ($fs = @fsockopen($host, $port, $errno, $errstr, 10))) { 
       die ('Could not open socket'); 
     } 

     fwrite($fs, $http_request); 

     while (!feof($fs)) 
       $response .= fgets($fs, 1160); // One TCP-IP packet 
     fclose($fs); 
     $response = explode("\r\n\r\n", $response, 2); 

     return $response; 
} 



/** 
* Gets the challenge HTML (javascript and non-javascript version). 
* This is called from the browser, and the resulting reCAPTCHA HTML widget 
* is embedded within the HTML form it was called from. 
* @param string $pubkey A public key for reCAPTCHA 
* @param string $error The error given by reCAPTCHA (optional, default is null) 
* @param boolean $use_ssl Should the request be made over ssl? (optional, default is false) 

* @return string - The HTML to be embedded in the user's form. 
*/ 
function recaptcha_get_html ($pubkey, $error = null, $use_ssl = false) 
{ 
    if ($pubkey == null || $pubkey == '') { 
     die ("To use reCAPTCHA you must get an API key from <a href='http://recaptcha.net/api/getkey'>http://recaptcha.net/api/getkey</a>"); 
    } 

    if ($use_ssl) { 
       $server = RECAPTCHA_API_SECURE_SERVER; 
     } else { 
       $server = RECAPTCHA_API_SERVER; 
     } 

     $errorpart = ""; 
     if ($error) { 
      $errorpart = "&amp;error=" . $error; 
     } 
     return '<script type="text/javascript" src="'. $server . '/challenge?k=' . $pubkey . $errorpart . '"></script> 

    <noscript> 
     <iframe src="'. $server . '/noscript?k=' . $pubkey . $errorpart . '" height="300" width="500" frameborder="0"></iframe><br/> 
     <textarea name="recaptcha_challenge_field" rows="3" cols="40"></textarea> 
     <input type="hidden" name="recaptcha_response_field" value="manual_challenge"/> 
    </noscript>'; 
} 




/** 
* A ReCaptchaResponse is returned from recaptcha_check_answer() 
*/ 
class ReCaptchaResponse { 
     var $is_valid; 
     var $error; 
} 


/** 
    * Calls an HTTP POST function to verify if the user's guess was correct 
    * @param string $privkey 
    * @param string $remoteip 
    * @param string $challenge 
    * @param string $response 
    * @param array $extra_params an array of extra variables to post to the server 
    * @return ReCaptchaResponse 
    */ 
function recaptcha_check_answer ($privkey, $remoteip, $challenge, $response, $extra_params = array()) 
{ 
    if ($privkey == null || $privkey == '') { 
     die ("To use reCAPTCHA you must get an API key from <a href='http://recaptcha.net/api/getkey'>http://recaptcha.net/api/getkey</a>"); 
    } 

    if ($remoteip == null || $remoteip == '') { 
     die ("For security reasons, you must pass the remote ip to reCAPTCHA"); 
    } 



     //discard spam submissions 
     if ($challenge == null || strlen($challenge) == 0 || $response == null || strlen($response) == 0) { 
       $recaptcha_response = new ReCaptchaResponse(); 
       $recaptcha_response->is_valid = false; 
       $recaptcha_response->error = 'incorrect-captcha-sol'; 
       return $recaptcha_response; 
     } 

     $response = _recaptcha_http_post (RECAPTCHA_VERIFY_SERVER, "/verify", 
              array (
               'privatekey' => $privkey, 
               'remoteip' => $remoteip, 
               'challenge' => $challenge, 
               'response' => $response 
               ) + $extra_params 
             ); 

     $answers = explode ("\n", $response [1]); 
     $recaptcha_response = new ReCaptchaResponse(); 

     if (trim ($answers [0]) == 'true') { 
       $recaptcha_response->is_valid = true; 
     } 
     else { 
       $recaptcha_response->is_valid = false; 
       $recaptcha_response->error = $answers [1]; 
     } 
     return $recaptcha_response; 

} 

/** 
* gets a URL where the user can sign up for reCAPTCHA. If your application 
* has a configuration page where you enter a key, you should provide a link 
* using this function. 
* @param string $domain The domain where the page is hosted 
* @param string $appname The name of your application 
*/ 
function recaptcha_get_signup_url ($domain = null, $appname = null) { 
    return "http://recaptcha.net/api/getkey?" . _recaptcha_qsencode (array ('domain' => $domain, 'app' => $appname)); 
} 

function _recaptcha_aes_pad($val) { 
    $block_size = 16; 
    $numpad = $block_size - (strlen ($val) % $block_size); 
    return str_pad($val, strlen ($val) + $numpad, chr($numpad)); 
} 

/* Mailhide related code */ 

function _recaptcha_aes_encrypt($val,$ky) { 
    if (! function_exists ("mcrypt_encrypt")) { 
     die ("To use reCAPTCHA Mailhide, you need to have the mcrypt php module installed."); 
    } 
    $mode=MCRYPT_MODE_CBC; 
    $enc=MCRYPT_RIJNDAEL_128; 
    $val=_recaptcha_aes_pad($val); 
    return mcrypt_encrypt($enc, $ky, $val, $mode, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"); 
} 


function _recaptcha_mailhide_urlbase64 ($x) { 
    return strtr(base64_encode ($x), '+/', '-_'); 
} 

/* gets the reCAPTCHA Mailhide url for a given email, public key and private key */ 
function recaptcha_mailhide_url($pubkey, $privkey, $email) { 
    if ($pubkey == '' || $pubkey == null || $privkey == "" || $privkey == null) { 
     die ("To use reCAPTCHA Mailhide, you have to sign up for a public and private key, " . 
      "you can do so at <a href='http://mailhide.recaptcha.net/apikey'>http://mailhide.recaptcha.net/apikey</a>"); 
    } 


    $ky = pack('H*', $privkey); 
    $cryptmail = _recaptcha_aes_encrypt ($email, $ky); 

    return "http://mailhide.recaptcha.net/d?k=" . $pubkey . "&c=" . _recaptcha_mailhide_urlbase64 ($cryptmail); 
} 

/** 
* gets the parts of the email to expose to the user. 
* eg, given johndoe@example,com return ["john", "example.com"]. 
* the email is then displayed as john...@example.com 
*/ 
function _recaptcha_mailhide_email_parts ($email) { 
    $arr = preg_split("/@/", $email); 

    if (strlen ($arr[0]) <= 4) { 
     $arr[0] = substr ($arr[0], 0, 1); 
    } else if (strlen ($arr[0]) <= 6) { 
     $arr[0] = substr ($arr[0], 0, 3); 
    } else { 
     $arr[0] = substr ($arr[0], 0, 4); 
    } 
    return $arr; 
} 

/** 
* Gets html to display an email address given a public an private key. 
* to get a key, go to: 
* 
* http://mailhide.recaptcha.net/apikey 
*/ 
function recaptcha_mailhide_html($pubkey, $privkey, $email) { 
    $emailparts = _recaptcha_mailhide_email_parts ($email); 
    $url = recaptcha_mailhide_url ($pubkey, $privkey, $email); 

    return htmlentities($emailparts[0]) . "<a href='" . htmlentities ($url) . 
     "' onclick=\"window.open('" . htmlentities ($url) . "', '', 'toolbar=0,scrollbars=0,location=0,statusbar=0,menubar=0,resizable=0,width=500,height=300'); return false;\" title=\"Reveal this e-mail address\">...</a>@" . htmlentities ($emailparts [1]); 

} 


?> 

Answer 1

This chapter из документации ReCaptcha содержит информацию о настройке внешнего вида ReCaptcha.