From http://www.white-hat-web-design.co.uk/blog/resizing-images-with-php/

new_gist_file_0

<?php
   if( isset($_POST['submit']) ) {
 
      include('SimpleImage.php');
      $image = new SimpleImage();
      $image->load($_FILES['uploaded_image']['tmp_name']);
      $image->resizeToWidth(150);
      $image->output();
   } else {
 
?>
 
   <form action="upload.php" method="post" enctype="multipart/form-data">
      <input type="file" name="uploaded_image" />
 
      <input type="submit" name="submit" value="Upload" />
 
   </form>
 
<?php
   }
?>