Código PHP:
$con = "BCDFGHJKLMNÑOPQRSTVWXYZ";
$voc = "AEIOU";
$num ="1234567890";
for ($x=0; $x < 6; $x++) {
$con[$x] = substr($con, mt_rand(0, strlen($con)-1), 1);
$voc[$x] = substr($voc, mt_rand(0, strlen($voc)-1), 1);
$num[$x] = substr($num, mt_rand(0, strlen($num)-1), 1);
}
$pass = $con[0] . $num[0] .$voc[0] . $num[0] . $num[0] . $voc[0] ;
$image = ImageCreateFromJPEG("code_bg.jpg");
$text_color = ImageColorAllocate($image, 0, 0, 0);//color rgb
Header("Content-type: image/jpeg");
ImageString ($image, 5, 12, 2, $pass, $text_color);
ImageJPEG($image, '', 75);
un Saludo
