//マウスオーバーで画像を切り替えるメソッド
var img1_on = new Image();
var img1_off = new Image();

function rollon(imagefile,targetimage){
		img1_on.src = "images/" + imagefile + ".jpg";
		document.images[targetimage].src = img1_on.src;
}

function rolloff(imagefile,targetimage) {
		img1_off.src = "images/" + imagefile + ".jpg";
		document.images[targetimage].src = img1_off.src;
}