function getanImage()
{
    var ranNum= Math.floor(Math.random()*7);

    var middle = new Array(7)
     middle[0]= "images/ri1.jpg";
     middle[1]= "images/ri2.jpg";
     middle[2]= "images/ri3.jpg"; 
     middle[3]= "images/ri4.jpg";
     middle[4]= "images/ri5.jpg";
     middle[5]= "images/ri6.jpg";
     middle[6]= "images/ri7.jpg";
	
	document.middle_img.src = middle[ranNum]; 
	    
   }