gistfile1.txt

    <?php
    /**
     * Anti-spam
     */
    public function antiSpamAction()
    {
        $lenght=6;
        $number = ""; 
        for ($i = 1; $i <= $lenght; $i++) 
        { 
             $number .= rand(0,9).""; 
        } 
        $width = 11*$lenght; 
        $height = 30; 

        $img = ImageCreate($width, $height); 
        $background = imagecolorallocate($img,255,255,255); 
        $color_black = imagecolorallocate($img,0,0,0); 
        $color_grey = imagecolorallocate($img,169,169,169); 
        imagerectangle($img,0, 0,$width-1,$height-1,$color_grey); 
        imagestring($img, 5, $lenght, 7, $number, $color_black); 
        $_SESSION['anti-spam'] = $number;
        //////// VERY IMPORTANT 
        header('Content-Type: image/png'); 
        //////// VERY IMPORTANT 
        imagepng($img); 
        imagedestroy($img);
    }
?>