var imgPath="/northernireland/learning/eyewitness/images/bt/";

function preload(){
	if(document.images){
		imageObjects = new Array();
		for (i=0; i < arguments.length; i++){
			imageObjects[i] = new Image();
			imageObjects[i].src = imgPath+arguments[i];
}	}	}

function chng(img,src){
	if(document.images&&document.images[img]&&document.images[img].src){
		document.images[img].src=imgPath+src;
}	}

function swap(img){
	if(document.images){
		chng("roll_"+img,img+"_on.gif");
}	}

function unswap(img){
	if(document.images){
		chng("roll_"+img,img+".gif");
}	}