jQuery(document).ready(function($) {
    
    $('.lightbox_trigger').click(function(e) {
        
        e.preventDefault();
        var image_href = $(this).attr("href");
        
        if ($('#lightbox').length > 0) {
            
            $('#content_lightbox').html('<img src="' + image_href + '" />');
            
            $('#lightbox').show();
        }
        
        else {
            var lightbox =
            '<div id="lightbox">' +
                '<div id="br_lightbox"></div>' +
                '<div id="content_lightbox">' +
                    '<img class="lightbox_img" src="' + image_href +'" />' +
                '</div>' +   
            '</div><div id="dark_lightbox"></div>';
                
            $('body').append(lightbox);

        }
  $("#dark_lightbox").fadeTo(500, 0.7);
  $("#lightbox")[0].onclick = function(){ _finish(); };
  $("#content_lightbox")[0].onclick = function(){ _finish(); };
        
    });

 
   function _finish() {
   $('#lightbox').fadeOut(function() { $('#lightbox').remove(); });
   $('#dark_lightbox').fadeOut(function() { $('#dark_lightbox').remove(); });
  }

});

#lightbox {
    position:fixed;
    top:0px;
    left:0;
    width:100%;
    height:100%;
 z-index:9001;
    /*background:url(overlay.png) repeat;*/
    text-align:center;
}
#br_lightbox{padding-top:50px;}
#dark_lightbox{
    position:fixed;
    top:0px;
    left:0;
    width:100%;
    height:100%;
 z-index:9000;
    /*background:url(overlay.png) repeat;*/
    text-align:center;
 background-color:#000000;
}
#lightbox img {
    box-shadow:0 0 25px #111;
    -webkit-box-shadow:0 0 25px #111;
    -moz-box-shadow:0 0 25px #111;
    max-width:940px;
}
    .lightbox_img { width: expression((this.width > 940)? ((this.height > 750)? ((this.width < this.height)? true : 750) : 940) :true); height: expression((this.height > 750)? ((this.width > 940)? ((this.width > this.height)? true : 750) : 940) :true); max-width: 940px; max-height: 750px;}

<a class="lightbox_trigger" href="원본 이미지 주소" target="_blank"><img class="resize_img" src="보여질 이미지 주소" /></a>