se hai la possibilità di wrappare le immagini in un elemento, potresti risolvere così

codice:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="it" xml:lang="it">
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
        <title>xhtml 1.0</title>
     
        <style type="text/css">
        
        div {
            width   : 500px;
            border  : 1px solid #767676;
            text-align  : center;
        }
        
        p {
            text-align  : justify;
            margin      : 1.5em 0 0 0;
            padding     : 0;
        }

        ins {
            margin          : 1.5em 0 0 0;
            border          : 1px solid #767676;
            display         : block;
            text-align      : center;
        }

        </style>

    </head>

<body>

<div>
    


       Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. 
    </p>

    <ins>
        
    </ins>

    


    Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. 
    </p> 
    

    <ins>
        
        
    </ins>
</div>

</body>
</html>