I am currently using
<?php $src = wp_get_attachment_image_src( get_post_thumbnail_id($post->ID), array( 5600,1000 ), false, '' ); ?>
To display a featured image as a background image within a div.
But because of the way that WordPress displays background images I would prefer it only pull and load the "thumbmail" version, as apposed to uploading an additional image on each post that is already sized properly.
IS is possible to specify, within the code I am using, for it to pull only the thumb version, or a add_image_size called "Featured" that I have placed in my functions.php file.