var w_height=screen.availheight
var w_width=screen.availwidth
n_height=(w_height-425)/2
n_width=(w_width-500)/2

function openImage(imgName){
window.open("imgpopup.html?"+imgName+"","ImgPopup","toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=no,resizable=yes,height=550,width=600,left=" + n_width + ",top=" + n_height + "")
}