una/template/popup_image.html

<div class="bx-popup-image-container">
    <div class="bx-popup-image-btn bx-def-padding">
        <a class="bx-btn bx-def-margin-sec-left" title="<bx_text_attribute:_sys_close />" href="javascript:void(0);" onclick="$(this).parents().filter('.bx-popup-wrapper').dolPopupHide()"><i class="sys-icon times"></i></a>
    </div>

    <img class="bx-popup-image-image" src="__image_url__" />
</div>