首先, 利用前述的方式, 產生你的數字圖檔, 並選取一個背景圖檔. 在 include 的目錄下, 建立一個 chinese_img 的目錄, 把這些檔案放進去.

然後產生一個新的檔案 usercp_captcha_chinese.php, 放到 include, 內容如下:

<?php
 
if ( !defined('IN_PHPBB') )
{
        die('Hacking attempt');
        exit;
}
// Do we have an id? No, then just exit
if (empty($HTTP_GET_VARS['id']))
{
        exit;
}
 
$confirm_id = htmlspecialchars($HTTP_GET_VARS['id']);
 
if (!preg_match('/^[A-Za-z0-9]+$/', $confirm_id))
{
        $confirm_id = '';
}
 
$gd = true;
if(!extension_loaded("gd")){
        //Gd isn't loaded
        //Display error messages always, or not?
        $gd = false;
}
if(!function_exists("gd_info") || !function_exists('imagettftext')){
        //GD function, gd_info don't exists. GD isn't loaded correctly.
        //Freetype function imagettftext doesn't exists. This is required by this mod.
        $gd = false;
}
if($gd === false){
        //GD not loaded, or one of the needed functions aren't there. Require usercp_confirm ;)
        require($phpbb_root_path . 'includes/usercp_confirm.' . $phpEx);
        die;
}
 
// Try and grab code for this id and session
$sql = 'SELECT code
        FROM ' . CONFIRM_TABLE . "
        WHERE session_id = '" . $userdata['session_id'] . "'
                AND confirm_id = '$confirm_id'";
$result = $db->sql_query($sql);
 
// If we have a row then grab data else create a new id
if ($row = $db->sql_fetchrow($result))
{
        $db->sql_freeresult($result);
        $code = $row['code'];
}
else
{
        exit;
}
 
$len = strlen($code);
$im = ImageCreate(24 * $len, 24);
$background = ImageColorAllocate($im, 255, 255, 255);
 
$bg_file = $phpbb_root_path . 'includes/chinese_img/background.gif';
$im_bg = @ImageCreateFromGIF($bg_file);
if ($im_bg) {
    list($width, $height, $type, $attr) = @GetImageSize($bg_file);
    if (function_exists('ImageCopyReSampled'))
        ImageCopyReSampled($im, $im_bg, 0, 0, 0, 0, 24 * $len, 24, $width, $height);
    else
        ImageCopyReSized($im, $im_bg, 0, 0, 0, 0, 24 * $len, 24, $width, $height);
    ImageDestroy($im_bg);
}
 
for ($i = 0; $i < $len; $i++) {
    $im_num = @ImageCreateFromPNG($phpbb_root_path . 'includes/chinese_img/'.$code[$i].'.png');
    if ($im_num) {
        ImageColorTransparent($im_num, ImageColorAt($im_num, 0, 0));
        ImageCopy($im, $im_num, 24 * $i, 0, 0, 0, 24, 24);
        ImageDestroy($im_num);
    }
}
 
header("content-type:image/png");
header('Cache-control: no-cache, no-store');
 
ImagePNG($im);
ImageDestroy($im);
die;
 
?>

然後修改 include/usercp_register.php 的內容, 找到:

$code = dss_rand();

把下頭的 $code = substr(... 這行改成:

$code = substr(base_convert($code, 16, 10), 2, 6);

然後修改 profile.php 的內容, 找到:

include($phpbb_root_path . 'includes/usercp_confirm.'.$phpEx);

把這行改成:

include($phpbb_root_path . 'includes/usercp_captcha_chinese.'.$phpEx);

經過這樣子的修改, 應該就可以在註冊時看到那個圖片變成中文的數字了. 

那個新增的檔案與圖型檔, 也可以由這兒抓取: http://www.teatime.com.tw/~tommy/files/phpbb2_captcha_chinese.tgz  

把這個檔案在 include 目錄中解開就可以了.