need path of an image created using an image style
You can use image_style_url($style_name, $path)

Example:

$img_url = $node-&gt;field_image['und'][0]['uri'];
&lt;img src="&lt;?php print image_style_url("thumbnail", $img_url); ?&gt;" /&gt;


Where you will be replacing thumbnail with the image style name you have in place