<?php 
/********************************************** 
* Yazar     : Richard Harris 
* Web     : www.rtharris.com 
* Posta     : [email protected] 
* Tarih     : 16/02/06 
* Kullanım     : 
*           <img src=img.php> 
*           <img src=img.php?folder=images2/> 
***********************************************/ 
 
if($_GET['folder']){ 
     $folder=$_GET['folder']; 
}else{ 
     $folder='/images/'; 
} 
 
//Selected Folder Name
$path = $_SERVER['DOCUMENT_ROOT']."/".$folder; 
$files=array(); 
if ($handle=opendir("$path")) { 
     while(false !== ($file = readdir($handle))) {   
          if ($file != "." && $file != "..") {  
                     if(substr($file,-3)=='gif' || substr($file,-3)=='jpg') $files[count($files)] = $file; 
                } 
           }  
} 
closedir($handle);  
 
$random=rand(0,count($files)-1); 
if(substr($files[$random],-3)=='gif') header("Content-type: image/gif"); 
elseif(substr($files[$random],-3)=='jpg') header("Content-type: image/jpeg"); 
readfile("$path/$files[$random]"); 
?>
 
Usage :
It's very easy to use. Just copy the code to a new php file and save it "randomImages.php". 
 
Then where ever you would like to use and show your random images, use this way and don't forget to add folder name to a string.
<img src=randomImages.php?folder=randomFolder02/>