function getXmlHttpRequestObject() {
 if (window.XMLHttpRequest) {
  return new XMLHttpRequest();
 } else if(window.ActiveXObject) {
  return new ActiveXObject('Microsoft.XMLHTTP');
 } else { // regi a bongeszoje
 }
}

var http = getXmlHttpRequestObject();

function open_picture(path) {
 http.open('get', path);
 http.onreadystatechange = handleOpenPicture; 
 http.send(null);
}

function handleOpenPicture() {
 if (http.readyState == 4) {
  var response = http.responseText;
  document.getElementById('galeria').innerHTML = response;
 }
}