function initImgRotation() {
  var rotator1 = new rotateImgObj('img1',2500);
  rotator1.addImages("image1.jpg","image2.jpg","image3.jpg","image4.jpg","image5.jpg","image6.jpg","image7.jpg","image8.jpg","image9.jpg","image10.jpg");
  rotator1.rotate();
  var rotator2 = new rotateImgObj('img2',2400);
  rotator2.addImages("image11.jpg","image12.jpg","image13.jpg","image14.jpg","image15.jpg","image16.jpg","image17.jpg","image18.jpg","image19.jpg","image20.jpg");
  rotator2.rotate();
  var rotator3 = new rotateImgObj('img3',2300);
  rotator3.addImages("image21.jpg","image22.jpg","image23.jpg","image24.jpg","image25.jpg","image26.jpg","image27.jpg","image28.jpg","image29.jpg","image30.jpg");
  rotator3.rotate();
  var rotator4 = new rotateImgObj('img4',2200);
  rotator4.addImages("image31.jpg","image32.jpg","image33.jpg","image34.jpg","image35.jpg","image36.jpg","image37.jpg","image38.jpg","image39.jpg","image40.jpg");
  rotator4.rotate();
  rotateImgObj.start();
}

rotateImgObj.imagesPath = "images/";

rotateImgObjs = []; 
function rotateImgObj(nm,s) {
  this.speed=s; this.ctr=0; this.timer=0;  
  this.imgObj = document.images[nm];
  this.index = rotateImgObjs.length; rotateImgObjs[this.index] = this;
  this.animString = "rotateImgObjs[" + this.index + "]";
}

rotateImgObj.prototype = {
  addImages: function() {
    this.imgObj.imgs = [];
    for (var i=0; arguments[i]; i++) {
      this.imgObj.imgs[i] = new Image();
      this.imgObj.imgs[i].src = rotateImgObj.imagesPath + arguments[i];
    }
  },

  rotate: function() {
    if (this.ctr < this.imgObj.imgs.length-1) this.ctr++;
    else this.ctr = 0;
    this.imgObj.src = this.imgObj.imgs[this.ctr].src;
  }
}

rotateImgObj.start = function() {
  for (var i=0; i<rotateImgObjs.length; i++) 
    rotateImgObjs[i].timer = setInterval(rotateImgObjs[i].animString + ".rotate()", rotateImgObjs[i].speed);                     
}