Parralax

script.js

$( window ).scroll(function(){
    $('.banner-image[data-perspective]').each(function(){
      var perspective = $(this).data('perspective');
      var position = $(this).parents().position();
      var scrollTop = position.top - $(window).scrollTop();
      var height = $(this).outerHeight();
      var calc = $(this).outerHeight() - height - scrollTop ;
      $(this).css({'transform': 'translate3d(0px, ' + Math.round(calc/perspective) + 'px, 0px)'});
    });
});