<script language='javascript'>  
function show(path)  
{  
    if (obj = document.getElementById('pic')) {  
        obj.src = path; }  
            if (obj = document.getElementById('link')) {  
        obj.href = path; }  

}  
</script>  

<img id="pic" src = "foto/$foto" >  
<p>
<a href="$foto" id="link" target="_blank">Посмотреть  оригинал</a>
</p>            
        

            <a href='#' onClick="show('foto/img.jpg'); return  false;">
<img src='foto/img.jpg' title='' alt=''  />
</a>