$(window).resize(function(){
		setImagesTopMargin();
	});

	$('.slider > div .photos img').each( function( ){

		if($(window).width()>640)
		{
			var ratio = $(this).attr('data-width')/$(this).attr("data-height");
			var newHeight = $(window).width()/ratio;
			var marginTop = newHeight/(-2);
			$(this).css("margin-top", marginTop+"px");
		}
	} );