function hide_loader() {
		document.getElementById("loading").style.display="none"; 
	 }
	 
	function setPic(id, file, cat, description) {
	    document.getElementById("mainpic").src="pictures/" + cat + "/" + file;
		document.getElementById("loading").style.display="block";
		document.getElementById("description").innerHTML=description;
		document.getElementById("mainpic").onload = function() {
			hide_loader();
		}
	 }