<?php
session_start();


function captcha($length) {

    // generate a totally random string using md5
    $rd = md5(rand(0, 999)); 
   
    // We don't need a 32 character long string so we trim it down to 5  because md5 will return a long string
    $code = substr($rd, 15, $length); 

    // Set the session to store the security code
    $_SESSION["captcha"] = $code;

    // Set the image width and height
    $width = 200;
    $height = 50;

    // Create the image resource 
    $image = imagecreate($width, $height);
   
    // Random RGB colours
    $rgb1 = rand(0, 255);
    $rgb2 = rand(0, 255);
    $rgb3 = rand(0, 255);

    $background = imagecolorallocate($image, $rgb1, $rgb2, $rgb3);
    $text = imagecolorallocate($image, ($rgb1 - 60), ($rgb2 - 60), ($rgb3 - 60));

    // Make the background colour
    imagefill($image, 0, 0, $background); 
        for ($i = 0; $i < 10; $i++) {
$rx1 = rand(0,$width);
$rx2 = rand(0,$width);
$ry1 = rand(0,$height);
$ry2 = rand(0,$height);
$rcVal = rand(0,255);
$rc1 = imagecolorallocate($image,
rand(0,255),
rand(0,255),
rand(100,255));
//giving noise
imageline ($image, $rx1, $ry1, $rx2, $ry2, $rc1);
}

    // Add randomly generated string in the image
    for($i = 1; $i <= $length; $i++) {
        $counter = rand(1, 2);
         
        if ($counter == 1) {
            $angle = rand(0, 45);
        }
        if ($counter == 2) {
            $angle = rand(315, 360);
        }
         
imagettftext($image, rand(14, 20), $angle, ($i * 25), 30, $text, "font/LucidaBrightDemiItalic.ttf", substr($code, ($i - 1), 1));
    }

    // Add a border
    imagerectangle($image, 0, 0, $width - 1, $height - 1, $text); 
 
    // Tell the browser what kind of file is come in 
    header("Content-Type: image/png"); 

    // Output the newly created image in jpeg format 
    imagepng($image);
   
    // Free up resources
    imagedestroy($image); 
}
/* pass  how many cahracter do you want your user can see*/

captcha(6);//i have pass 6 where user
?>