کلا کد بررسی کپچا رو پاک کن و این کد رو جایگزین کن :
header('Content-type: image/jpeg');
$width = 70;
$height = 30;
$my_image = imagecreatetruecolor($width, $height);
imagefill($my_image, 0, 0, 0xFFFFFF); // add noise
for ($c = 0; $c < 40; $c++){
$x = rand(0,$width-1);
$y = rand(0,$height-1);
imagesetpixel($my_image, $x, $y, 0x000000);
}
$x = rand(1,10);
$y = rand(1,10);
$rand_string = rand(1000,9999);
imagestring($my_image, 5, $x, $y, $rand_string, 0x000000);
setcookie('tntcon',(md5($rand_string).'a4xn'));
imagejpeg($my_image);imagedestroy($my_image);