random image with session

i have a script random image and it's work OK, image is changing when user refresh page...
but I need a script which display random images with sessions, image change when user close browser...
how make this script with session...

Thanx!

script:
<?php

$path_to_images = "PATH"; // path for images
$default_img = "test.png"; // default image, when error on page

function getRandomImage($path, $img) {

if ( $list = getImagesList($path) ) {
mt_srand( (double)microtime() * 1000000 );
$num = array_rand($list);
$img = $list[$num];
}
return $path . $img;
}

function getImagesList($path) {
$ctr = 0;
if ( $img_dir = @opendir($path) ) {
while ( false !== ($img_file = readdir($img_dir)) ) {
// formati slik, ki jih prepozna
if ( preg_match("/(\.gif|\.jpg|\.png)$/", $img_file) ) {
$images[$ctr] = $img_file;
$ctr++;
}
}
closedir($img_dir);
return $images;
}
return false;
}

?>

<img src="<?php echo getRandomImage($path_to_images, $default_img) ?>" alt="">

 

use if(!isset($_SESSION['id'])) it will help you

call function when this variable is not set. So when you refresh the page it wont change. But when you close the explorer it will.