<a href="#" onclick="popWin('<?php echo $this->getGalleryUrl($_image) ?>', 'gallery', 'width=300,height=300,left=0,top=0,location=no,status=yes,scrollbars=yes,resizable=yes'); return false;" title="<?php echo $this->htmlEscape($_image->getLabel()) ?>"><img src="<?php echo $this->helper('catalog/image')->init($this->getProduct(), 'thumbnail', $_image->getFile())->resize(56); ?>" width="56" height="56" alt="<?php echo $this->htmlEscape($_image->getLabel()) ?>" /></a>

<p>To disable the popup image, <code>etc/view.xml</code> and change this code.</p>
<pre class="default prettyprint prettyprinted" style=""><code><span class="tag"><var</span><span class="pln"> </span><span class="atn">name</span><span class="pun">=</span><span class="atv">"gallery"</span><span class="tag">></span><span class="pln">
    </span><span class="tag"><var</span><span class="pln"> </span><span class="atn">name</span><span class="pun">=</span><span class="atv">"allowfullscreen"</span><span class="tag">></span><span class="pln">false</span><span class="tag"></var></span><span class="pln"> </span><span class="com"><!-- Turn on/off fullscreen (true/false) --></span><span class="pln">
    ...
</span><span class="tag"></var></span></code></pre>