How to disable lightbox for "big-preview" ?

Hello,

Could you please tell how to properly disable lightbox, so that the full size featured image cannot be clicked, for the following code inside loop-index.php:

//echo preview image
if(strpos($blog_style, ‘big’) !== false)
{
if($slider) $slider = ‘‘.$slider.’‘;
if($slider) echo ‘<div class=”big-preview ‘.$blog_style.'”>’.$slider.'</div>’;
}

if(!empty($before_content))
echo ‘<div class=”big-preview ‘.$blog_style.'”>’.$before_content.'</div>’;