function changeImage(imageNum)
	{
		var img = imageNum;
		var str = document.getElementById('mainimg').src;
        var str = str.replace(/large.*.jpg/i, "");
		elem = document.getElementById('mainimg').src=(str + 'large' + img + '.jpg');
}

function loadImages() {
    var str = document.getElementById('mainimg').src;
    var str = str.replace(/large.*.jpg/i, "");

    pic1 = new Image();
    pic1.src = str + "large1.jpg";

    pic2 = new Image();
    pic2.src = str + "large2.jpg";

    pic3 = new Image();
    pic3.src = str + "large3.jpg";

    pic4 = new Image();
    pic4.src = str + "large4.jpg";
}