function render_secret_image($random_num)
{
$gdImage = new GDImage(get_opendb_image_type());
$gdImage->createImage('code_bg');
$image =& $gdImage->getImage();
$text_color = ImageColorAllocate($image, 80, 80, 80);
header("Cache-control: no-store");
header("Pragma: no-store");
header("Expires: 0");
CenterImageString($image, 100, get_secret_image_code($random_num), 5, 7, $text_color);
$gdImage->sendImage();
unset($gdImage);
}