function changePhoto(page_id){
  	obj = document.getElementById('left_image');
  	obj2 = document.getElementById('footer');

	switch(page_id){
   	case 1:
	      obj.style.backgroundImage  = 'url(./_img/left/about.jpg)'
	      obj2.style.backgroundImage  = ''
	      break    
	   case 2:
	      obj.style.backgroundImage  = 'url(./_img/left/client.jpg)'
	      obj2.style.backgroundImage  = ''
	      break
	   case 3:
	      obj.style.backgroundImage  = 'url(./_img/left/methodology.jpg)'
	      obj2.style.backgroundImage  = ''
	      break
	   case 4:
	      obj.style.backgroundImage  = 'url(./_img/left/testimonials.jpg)'
	      obj2.style.backgroundImage  = ''
	      break
	   case 5:
	      obj.style.backgroundImage  = 'url(./_img/left/biographies.jpg)'
	      obj2.style.backgroundImage  = ''
	      break
	   case 6:
	      obj.style.backgroundImage  = 'url(./_img/left/contact.jpg)'
	      obj2.style.backgroundImage  = 'url(./_img/left/contact_right.jpg)'
	      break
	   default:

   }
}