if ($('small_image_1')) $('small_image_1').onmouseover = function() {swap_image($('small_image_1'));};
if ($('small_image_2')) $('small_image_2').onmouseover = function() {swap_image($('small_image_2'));};
if ($('small_image_3')) $('small_image_3').onmouseover = function() {swap_image($('small_image_3'));};
if ($('small_image_4')) $('small_image_4').onmouseover = function() {swap_image($('small_image_4'));};

function swap_image(element) {
  var image = element.src.replace(/[a-z\.\/:]/gi, '');
  $('main_page_image').src = '/dyn/detail/detail' + image +'.jpg';
}