Untitled

<html>
  <script type="text/javascript" src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
  <body>
    <form method="post" action="/test.php" enctype="multipart/form-data">
      <input type="hidden" name="base64" id="base64"></input>
      <input type="submit"></input>
    </form>

    <input type="file" name="fileSelector" id="fileSelector"></input><br/>
    <img id="original_image">
  </body>
  <script>
    $('#fileSelector').change(function(event) {
        var file = event.target.files[0];
        var reader = new FileReader();
        reader.readAsDataURL(file);

        reader.onload = function(event) {
          var base64 = reader.result;

          $('#base64').attr('value', base64);
          $('#original_image').attr('src', base64);
        }
    });
  </script>
</html>