function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}

}

function changeImages() {
	if (document.images && (preloadFlag == true)) {
		for (var i=0; i<changeImages.arguments.length; i+=2) {
			document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
		}

	}

}
<!-- Begin
pixa = new Array(6);
lowa = new Array(6);

var num = 0;
pixlowa = new Image();

pixa[0] = new Image();
pixa[1] = new Image();
pixa[2] = new Image();
pixa[3] = new Image();
pixa[4] = new Image();
pixa[5] = new Image();
pixa[6] = new Image();

lowa[0] = new Image();
lowa[1] = new Image();
lowa[2] = new Image();
lowa[3] = new Image();
lowa[4] = new Image();
lowa[5] = new Image();


pixa[0] = "images/img1.jpg";
pixa[1] = "images/img2.jpg";
pixa[2] = "images/img3.jpg";
pixa[3] = "images/img4.jpg";
pixa[4] = "images/img5.jpg";
pixa[5] = "images/img6.jpg";


function doImages() 

{ 
num = getRandomNum(0, 6); 
document['npixa'].lowsrc=lowa[num]; 
document['npixa'].src=pixa[num]; 
} 

function getRandomNum(lbound, ubound) 

{
	return (Math.floor(Math.random() * (ubound - lbound)) + lbound);

}