Block render array image_formatter
$image = array(
  '#theme' =&gt; 'image_formatter',
  '#image_style' =&gt; 'thumbnail',
  '#item' =&gt; array(
    'uri' =&gt; $user-&gt;picture-&gt;uri,
    'alt' =&gt; '',
    'title' =&gt; '',
  ),
);
$block['image'] = $image;