title: Get image type url with Wordpress Media Upload
body: <p>I can't seem to retrieve a specific image type, like thumbnail, thumb, or post-thumbnail with Wordpress Media Upload.</p>
  
  <p>All I get is the images original size url, and because of that I show a huge image instead of a thumbnail or a defined image size.</p>
  
  <p>This is my script:</p>
  
  <pre><code>jQuery("#submit_logo_button").click(function(e){
  e.preventDefault();
  var custom_file_frame;
  if (typeof(custom_file_frame)!=="undefined") {
       custom_file_frame.close();
    }
  
    //Create WP media frame.
    custom_file_frame = wp.media.frames.customHeader = wp.media({
       //Title of media manager frame
       title: "Thumbs - Choose Logo",
       library: {
          type: 'image'
       },
       button: {
          //Button text
          text: "Select Logo"
       },
       size: "post-thumbnail",//shouldn't this work?!?
       //Do not allow multiple files, if you want multiple, set true
       multiple: false
    });
  
    //callback for selected image
    custom_file_frame.on('select', function() {
       var attachment = custom_file_frame.state().get('selection').first().toJSON();
       jQuery("#image_thumbnail").attr("src", attachment.url);
  
    });
  
    //Open modal
    custom_file_frame.open();
  </code></pre>
  
  <p>});</p>
  
  <p>Thankyou :)</p>