Changing Image Names

I there a way I can change the name of the file to a random generated code?

Is there also a way so that I can upload .gif, .png, .bmp? I use this code to upload now, so can someone show me how to do this?

THanks in advance:



<?php
        if(isset($_POST['submit'])){
          if (isset ($_FILES['new_image'])){
              $imagename = $_FILES['new_image']['name'];
              $source = $_FILES['new_image']['tmp_name'];
              $target = "images/".$imagename;
              move_uploaded_file($source, $target);
 
              $imagepath = $imagename;
              $save = "upload_pic/" . $imagepath; //This is the new file you saving
              $file = "images/" . $imagepath; //This is the original file
 
              list($width, $height) = getimagesize($file) ; 
 
              $modwidth = 280; 
 
              $diff = $width / $modwidth;
 
              $modheight = $height / $diff; 
              $tn = imagecreatetruecolor($modwidth, $modheight) ; 
              $image = imagecreatefromjpeg($file) ; 
              imagecopyresampled($tn, $image, 0, 0, 0, 0, $modwidth, $modheight, $width, $height) ; 
 
              imagejpeg($tn, $save, 100) ; 
 
              $save = "upload_pic/" . $imagepath; //This is the new file you saving
              $file = "images/" . $imagepath; //This is the original file
 
              list($width, $height) = getimagesize($file) ; 
 
              $modwidth = 280; 
 
              $diff = $width / $modwidth;
 
              $modheight = $height / $diff; 
              $tn = imagecreatetruecolor($modwidth, $modheight) ; 
              $image = imagecreatefromjpeg($file) ; 
              imagecopyresampled($tn, $image, 0, 0, 0, 0, $modwidth, $modheight, $width, $height) ; 
 
              imagejpeg($tn, $save, 100) ; 
            echo "Thumbnail: <img src='upload_pic/".$imagepath."'>"; 
 
          }
        }
?><