<?php 

session_start(); 

$ch = array("a","b","c","D","e","F","G","h","i","J","k","L","m","n","O","4","1","Z", "B", "9", "2");//цифры и буквы капчи капчи 

$cap = ''; 

for($i=0; $i < 6; $i++){ 

$cap .= $ch[rand(0, 20)]; 

$_SESSION['cap'] = $cap; 

} 

$img = imagecreate('60', '30'); 

$back = imagecolorallocate($img, rand(100, 255), rand(100, 255), rand(100, 255)); 

$black = imagecolorallocate($img, rand(0, 255), rand(0, 255), rand(0, 255)); 

imagestring($img, rand(3, 9), rand(0, 6), rand(0, 6), $cap, $black); 

header('Content-type: image/png'); 

imagepng($img); 

imagedestroy($img); 

?>