var i, imgs, pic;

function rotate()
{
  pic.src = imgs[i] ;
  (i === (imgs.length -1) ) ? i=0 : i++ ;
  setTimeout( rotate, 4000 ); 
}

function init()
{
  pic = document.getElementById("pic");
 
  imgs = [ 
  "images/Wall-Art-Trevor.gif", 
  "images/Wall-Art-Prout.gif", 
  "images/Wall-Art-Ayo.gif", 
  "images/Wall-Art-Trees.gif", 
  "images/Wall-Art-Bucklers.gif", 
  "images/Wall-Art-Caunt.gif", 
  "images/Wall-Art-Hero.gif", 
  "images/Wall-Art-Lake.gif", 
  "images/Wall-Art-Beech.gif", 
  "images/Wall-Art-Pixof.gif", 
  "images/Wall-Art-Shenac.gif", 
  "images/Wall-Art-Flowers.gif" ] ;

  var preload= new Array();
  for( i=0; i< imgs.length; i++ )
  {
    preload[ i ] = new Image();
    preload[ i ].src = imgs[ i ];
  }

  i=0;

  rotate();
}
onload=init;