function changeColor(id,cid,size,side){
  if (!isNumeric(id) || !isNumeric(cid)){return;}
  if (id == 0 || cid == 0){return;}
  var el = document.getElementById("img" + id.toString());
  if (!el){return;}
  var link = "http://www.shirtshop.nl/stock/shop/" + size + "/";
  if (side != ""){link += side + "__";}
  link += cid.toString() + "__" + id.toString() + ".jpg";
  el.src = link;
}