$(function() {
    var $container = $('#am-container'),
           $imgs = $container.find('img').hide(),
           totalImgs = $imgs.length,
           cnt = 0;

        $imgs.each(function(i) {
            var $img = $(this);
            $('<img/>').load(function() {
                ++cnt;
                if (cnt === totalImgs) {
                    $imgs.show();
                    $container.montage({
                        fillLastRow: true,
                        alternateHeight: true,
                        alternateHeightRange: {
                            min: 75,
                            max: 300
                        }
                    });

                    /*
                     * just for this demo:
                     */
                    $('#overlay').fadeIn(500);
                }
            }).attr('src', $img.attr('src'));
        });

    });

<div class="main-gallary">
   <div class="container">
      <div id="am-container" class="am-container">
          <a href="#">
             <img class="ui-draggable" src="images/gallary/img-1.jpg" style="display: inline; position: relative;">
          </a>
          <a href="#">
          <a href="#">
     </div>
   </div>
</div>

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js"></script>

<script type="text/javascript" src="js/jquery.montage.min.js"></script>