Drupal - get the path of an image without resorting to modules / Custom views-view--fields template

research.txt

Views template API docs:
https://api.drupal.org/api/views/theme!theme.inc/group/views_templates/7

Function file_create_url:
https://api.drupal.org/api/drupal/includes%21file.inc/function/file_create_url/7

Function field_get_items:
https://api.drupal.org/api/drupal/modules%21field%21field.module/function/field_get_items/7

sample-code.tpl.php

<?php 
  // Get our node id
	$node = node_load($row->nid);
	// Grab an array of field items for field_image
	$featuredImage = field_get_items('node', $node, 'field_image');
	// Create a url from our uri
	$featuredImage = file_create_url($featuredImage[0]['uri']);
?>
<div>
  <div style="background-image: url('<?php print $featuredImage; ?>');">
  	<header>
    	<h1><?php print $fields['title']->content; ?></h1>
    	<h2><?php print $fields['field_subtitle']->content; ?></h2>
    </header>
  </div>
</div>