var win = null;
var w = 760 ;
var h = 540 ;
function popup (img){
LeftPosition = (screen.width) ? (screen.width-w)/2 : 0 ;
TopPosition = (screen.height) ? (screen.height-h)/2 : 0 ;
settings = "height="+h+",width="+w+",top="+TopPosition+",left="+LeftPosition+",scrollbars=yes,resizable=yes" ;
win = window.open("galeria.aspx?n="+img,"galeria",settings) ;
}