function swapimage (img_name, op)	{
		if (op == 1)	{
			cmd = "document." + img_name + ".src = " + img_name + "_lo.src"
		}	
		else if (op == 2)	{
			cmd = "document." + img_name + ".src = " + img_name + "_hi.src"
		}
		else if (op == 3)	{
			cmd = "document." + img_name + ".src = " + img_name + "_sp.src"
		}
		eval (cmd)	
	}