How to display node image in page header for custom theme?
You can find @var $node on page.tpl.php. you can display your field using this code.

&lt;?php 
if(isset($node-&gt;field_review_nationality) &amp;&amp; !empty($node-&gt;field_review_nationality['und'][0]['uri'])) {
   &lt;img src="&lt;?php print file_create_url($node-&gt;field_review_nationality['und'][0]['uri']); ?&gt;"/&gt;
} 
?&gt;


If you have a style of the image then you can display using below code.

&lt;?php print theme('image_style', array('path' =&gt; $node-&gt;field_review_nationality['und'][0]['uri'], 'style_name' =&gt; [STYLE NAME])); ?&gt;