function preloadImages()
	{
		for(i=6;i<=21;i++)
		{
			eval("var image_"+i+" = new Image(); image_"+i+".src = 'images/index_on_"+i+".gif';");
		}
	}
	function swapImage(id, state)
	{
		document.images["image_"+id].src = "images/index"+state+"_"+id+".gif";
	}	
	function preloadImagesInner()
	{
		for(i=5;i<=10;i++)
		{
			eval("var image_"+i+" = new Image(); image_"+i+".src = 'images/inner_on_"+i+".gif';");
		}
	}
	function swapImageInner(id, state)
	{
		document.images["image_"+id].src = "images/inner"+state+"_"+id+".gif";
	}
	function showLayer()
	{
		document.getElementById("menu").style.display = "block";
	}
	function hideLayer()
	{
		document.getElementById("menu").style.display = "none";
	}
	function showLayerI()
	{
		document.getElementById("menu_i").style.display = "block";
	}
	function hideLayerI()
	{
		document.getElementById("menu_i").style.display = "none";
	}
	function showLayerII()
	{
		document.getElementById("menu_ii").style.display = "block";
	}
	function hideLayerII()
	{
		document.getElementById("menu_ii").style.display = "none";
	}
	function preloadImagesI()
	{
		for(i=6;i<=21;i++)
		{
			eval("var image_"+i+" = new Image(); image_"+i+".src = 'images/illusions/index_on_"+i+".gif';");
		}
	}
	function swapImageI(id, state)
	{
		document.images["image_"+id].src = "images/illusions/index"+state+"_"+id+".gif";
	}	
	
	function preloadImagesInnerI()
	{
		for(i=7;i<=10;i++)
		{
			eval("var image_"+i+" = new Image(); image_"+i+".src = 'images/illusions/inner_on_"+i+".gif';");
		}
	}
	function swapImageInnerI(id, state)
	{
		document.images["image_"+id].src = "images/illusions/inner"+state+"_"+id+".gif";
	}