Problem with pop up windows

Hello, I have an image gallery with little image buttons. I want this buttons to open the large image in pop up windows but the images have different sizes and when I open a pop up with an image and later I push another button with a different sized image, the pop up window doesn´t change his size. I don´t want to be all the time open and closing windows. This is the code i´m using:

on (release) {
getURL(
javascript:openNewWindow(‘http://www.one.htm,‘thewin25’,‘height=
413,width=550,top=’+((screen.height/2)-(213))+’,
left=’+((screen.width/2)-(550))+’,toolbar=no,scrollbars=no’)

in html :

<script language=“JavaScript”>

function openNewWindow(URLtoOpen, windowName, windowFeatures) { newWindow=window.open(URLtoOpen, windowName, windowFeatures); }

</script>