function doLoad(numimg) {
if (screen.availWidth){
	a=(screen.availWidth -600)/2;
	b=(screen.availHeight -500)/2-50;
}else{
	a=0;
	b=0;
}
window.open(numimg,'','menubar=no,scrollbars=yes,resizable=yes,width=600,height=500,top='+b+',left='+a);
}