if ((int)$category['level_depth'] == 2)
{
    $files = scandir(_PS_CAT_IMG_DIR_);

    if (count($files) > 0)
    {
        $html .= '<li id="category-thumbnail">';

        foreach ($files as $file)
            if (preg_match('/'.$category['id_category'].'-([0-9])?_thumb.jpg/i', $file) === 1)
                $html .= '|<div><img src="'.$this->context->link->getMediaLink(_THEME_CAT_DIR_.$file)
                .'" alt="'.Tools::SafeOutput($category['name']).'" title="'
                .Tools::SafeOutput($category['name']).'" class="imgm" /></div>|';

        $html .= '</li>';
    }
}