Simple parallax. Regardless of where the image is placed on the page this jQuery dependant Javascript will scroll from top to bottom of the background-image of the div containing the parallax image. Adopted from: http://net.tutsplus.com/tutorials/html-css-techniques/simple-parallax-scrolling-technique/

parallax.js

$(document).ready(function() {

	var $window = $(window); 
	var wH = $window.height();
	var docH = $(document).height();

	$('.CLASS-OF-PARALLAX-IMAGE-HERE').each(function(){  // edit the class name of the div containing the parallax image.
		var $bgobj = $(this); 
		$(window).scroll(function() {
			var coords, yCoord;
			var bgoff = $bgobj.offset().top;
			var bgH = $bgobj.height();
			var ws = $window.scrollTop();
			if ( bgoff > ws + wH ) {
				yCoord = 0;
			} else if ( ws > bgoff + bgH ) {
				yCoord = 100;
			} else {
				if ( wH + ws > bgoff && docH - bgoff - bgH < wH ) {
					yCoord = (ws + wH - bgoff) / (docH - bgoff);
				} else {
					yCoord = ws / (bgoff + bgH);
				}
				yCoord *= 100;
			}
			coords = '50% '+ yCoord + '%';				
			$bgobj.css({ backgroundPosition: coords });
		});
	});
});