var mywindow;
function ShowPreview(ImageFileName, SizeH, SizeW)
	{
		
		var windowprops = "location=no,scrollbars=no,menubars=no,toolbars=no,resizable=yes,left=" + ((screen.width - (SizeW + 0)) / 2) + ",top=" + ((screen.height - (SizeH + 0)) / 2) + ",width=" + (SizeW + 0) + ",height=" + (SizeH + 0);
		var URL = ImageFileName;
		
		if (!(mywindow == null))
			mywindow.window.close();
		mywindow = window.open(URL, "Preview", windowprops);
	}