window.onload = function () {
	FullScreenBackground('#bgimg');
	}
	$(window).resize(function() {
	FullScreenBackground('#bgimg');
	});
function FullScreenBackground(theItem){
	var winWidth=$(window).width();
	var winHeight=$(window).height();
	var imageWidth=$(theItem).width();
	var imageHeight=$(theItem).height();
	var picHeight = imageHeight / imageWidth;
	var picWidth = imageWidth / imageHeight;

	if ((winHeight / winWidth) < picHeight) {
		$(theItem).css("width",winWidth);
		$(theItem).css("height",picHeight*winWidth);
	} 
	else 
	{
		$(theItem).css("height",winHeight);
		$(theItem).css("width",picWidth*winHeight);
	};

	$(theItem).css("margin-left",winWidth / 2 - $(theItem).width() / 2);
	$(theItem).css("margin-top",winHeight / 2 - $(theItem).height() / 2);
}