function showImage(img,title,winwidth,winheight) {
    if (winheight == null) {
      winheight = '480';
    }
    if (winwidth == null) {
        winwidth = '640';
    }
    url = 'showImage.php?img=' + img + '&title=' + title + '&width=' + winwidth + '&height=' + winheight;
    window.open(url,'', 'toolbar=0,location=0,directories=0,status=0,menubar=0,scrollbars=0,resizable=0,width='+winwidth+',height='+winheight);
}